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Here’s my long, sad tale of misery ….hope someone has the answers: My 1992 626LX sedan is only blowing warm air ..and I’m getting worried now as the minus 30 stuff is well on its way!! (Western Canada)
This past weekend I drained the old coolant, took the old thermostat out, added a can of coolant system flush, re-filled the system with clean water, ran it for 20 minutes, drained out the water & flush stuff, and then also disconnected the heater core hose (top one), pinched the bottom hose closed and poured more coolant flush & water mix into the heater core, let it sit for 30 minutes, and then drained. Took off the bottom core hose, and blew air through the core, put the hoses back on, put a new thermostat in, filled with new 50-50 coolant distilled water mix. And now I see no improvement in the heat coming from the heater. The temp gauge goes up to above half-way when the car has run for about 5 minutes on the highway, but there’s very little warmth being kicked out of the heater. Did I get a bad thermostat? Do I need a new rad cap?
The blower motor is kicking out slightly warm air only. All four speeds work on the blower as well. When I set the air selector to “recirculate” (meaning I’m re-using interior air) it doesn’t get any warmer either. I’m thinking maybe the flap in the heater system is not aligning correctly, and letting in too much cold air from the outside, and thereby cooling the heated air from the heater core before it gets into the car.
I took the car for a spin down the highway a couple of miles. Starting off (because the engine was warmed up) I had decent warm air coming out of the heater, but as soon as I got to highway speed (100 kmh) the airflow cooled off considerably. I switched the heater control from HOT to COLD …and the airflow went completely cold. The back to HOT, and the airflow warmed a bit. That tells me the valve in the heater core that controls coolant flow is working properly (right?). Got back from my test drive, and checked the hoses again: top rad hose fairly warm …bottom rad hose still just warmish. What the H**L does that mean? Blocked rad core?? I just flushed it out a week or so back …no indication that it was blocked. ????
Yesterday was a frustrating afternoon. 1. I drained the coolant and took out the new thermostat that I had installed earlier, and did the boiling water trick. It opened fully at 193 degrees. (I put the thermostat in a 1 litre pyrex container of water and microwaved it until the water was boiling. Then I used a digital candy thermometer to measure the temperature.) So, I was able to confirm that the thermostat was working properly. (tested the one I took out …the OEM two-stage type …it was working okay too. $21 wasted there).
2. I put the thermostat back in, and then put the coolant back into the system. Warmed the car up until the cooling fan came on….temp gauge was on the high side of the midrange on the gauge. At that point, the heater was putting out a decent amount of heat (but it was +4C outside!).
3. This time, as I had warmed up the car until the cooling fans came on, the bottom rad hose was hot as well: so, I know the rad is not blocked; the thermostat was functioning properly.
4. I took the car for a spin down the highway again ….and still not very much heat at highway speed. I realize this could partially be a result of the coolant cooling down a bit, but the temp gauge did not move appreciably. But still very weird.
5. As a last resort, I tried the old red-neck winter fix: cardboard in front of the rad. I cut a piece of corrugated cardboard and covered about 90% of the radiator ..cardboard right against the rad. Did the road test again, and surprisingly the output from the heater remained considerably warmer. I know that it was +4C (+39F) yesterday, and that would clearly impact how well the heater worked …so I’m anxious to see if this fix will hold up when it gets down to -35C again.
So …after all this, I still haven’t nailed down the exact cause of this problem …… input please???
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UPDATE
Wow ….this is continuing to be a VERY FRUSTRATING situation!
This morning I did a BTBB (by the book burp) of the cooling system with the spill-proof funnel: elevated the front end of the car so the rad cap was the highest point of the cooling system; installed the funnel; pinched off the hose to the expansion/overflow tank; warmed the car up at 2500 rpm until the cooling fan came on; massaged the upper and lower rad hoses; massaged the heater core hoses; left the heater control turned max, with blower fan off. All the hoses heated up as they should with hot coolant flowing through them. There were a very few minor bubbles (pea sized) released into the funnel, but not the BURP that I expected. I revved the car at 4000 rpm for a few minutes ..no more bubbles. So, I let it cool down a bit, took the clamp off the expansion tank hose, and let the funnel coolant drain into the expansion tank. Then I removed the funnel, replaced the rad cap, and took the car for a high speed (70 mph) five mile run. Starting off, the system gave a good amount of heat, because everything was still hot from the burping session, but once out on the highway, the airflow from the heating system cooled down considerably, and remained cool when I got back and drove slower for a couple of miles.
So …I got into the centre stack on the dash. Took off the front console surround …removed the storage pocket, the ashtray, the radio, and took the screws out that hold the heating / cooling control center in place. You CANNOT see any of the heating system components by doing what I just described. And, you CANNOT remove the heating -cooling controls without first unhooking the control cable connections at the heater box end.
I removed the black cover panel under the driver side of the dash, and the plastic kick panel beside the gas pedal. This allowed me to see up to where the cables are connected to the white plastic gizmos that control the flap that controls where the air flows depending on the position of the lever on the dash (dash, front vents, floor vents, etc.). By moving the lever back and forth and observing the movement of the control flap, it appears that everything is working normally. Nothing appears out of place, and nothing appears to be broken.
So …now I’ve done it all …..and still no consist, continuous heat. !!!!!!!!!!!
What are my options now? …..wait til summertime and sell the car to someone who doesn’t drive in the winter???
In all my experiences in doing cooling system work, i have always had the heat on full with the blower on high. And i have never ‘pinched’ off the hose from the radiator to the expansion tank seeing as the cooling system will start to ‘draw’ in that coolant from that expansion tank.
Well ….maybe I screwed up, but here’s my reasoning for doing the BURP the way I did:
I went with the FAN OFF process because that’s what Eric recommends. He didn’t explain why, but I guessed it was common sense to assume that running the blower fan on high would only serve to cool down the coolant in the heater core when the whole point of the exercise was to heat up the coolant in the system.
I pinched off the coolant return line from the rad filler neck because I noted that as the funnel began to fill up with the expanding coolant, it was quickly draining off into the expansion tank, and I was concerned that (a) the expansion tank would simply overflow and drain onto the ground, and (b) there would not be enough coolant remaining in the funnel to observe any air bubbles coming out of the system.
If I didn’t run a technically valid BURP here, I’d certainly like to have the rest of you guys chime in an confirm that …..and I’d do it again a different way.
You don’t bleed systems with an expansion tank the same way you would one without, with those you want to use the expansion tank AS the spill free funnel so pinching off the line to it may have been a mistake. I can’t remember if that vehicle uses an expansion tank system.
As to leaving the blower fan OFF the reason for this is that if you leave it ON it will actually cool the system and it will take a LOT longer to bleed all the air out as well as for the cooling fans to come on if it has electric fans.
The next time you are experiencing this no heat condition feel the hoses going into the firewall for the heater core, they should both be warm if not hot to the touch, if they aren’t then there is either a problem with flow through the heater core due to blockage or air. If you do feel that both hoses are hot or warm then the problem may be with the airflow inside the HVAC system. By the sound of it however I don’t think this is likely since you seem to have heat for a time then it goes away, I think your problem is in the cooling system or heater core itself therefore I would recommend bleeding the cooling system again as suggested without pinching off the line to the expansion tank (BTW and expansion tank is pressurized, if it’s not pressurized it’s an ‘overflow tank’) so if you have just an overflow and not an expansion tank the bleed the system as shown in the video and disregard the part about the bleeder valve and see what you get.
This is above my head. I have absolutely no idea why he’s not getting heat. The 626 has bypass hoses so that coolant still circulates even if the thermostat hasn’t opened up. I imagine most engines has a similar design to help the car warm up during winter faster. His thermostat is obviously working right otherwise the heat wouldn’t disappear so fast while driving. Coolant temp sensor I believe he’s replaced. Sounds like for whatever reason that the engine isn’t able to produce enough heat to offset the -30F ambient temp while driving. I’m in FL so have no idea what’s that is like or what would cause that. Hope you get this fixed bro. -30F ain’t no joke.
ERIC: (1) yes, this vehicle, with the 2.2 four cylinder engine, uses an overflow tank system. (it is not pressurized like an “expansion tank” in an Olds Alero, for example) This vehicle has that kind of system where, when the coolant gets hot, it expands and flows into the overflow tank due to the pressure at the rad cap. And then, when the coolant cools and contracts in volume, the rad cap allows it to be sucked back into the rad and main cooling system. I have always kept the fluid level UP in the overflow tank so as not to allow air to be sucked back into the system when it cools off. Right now …with the engine cold, the tank is about midway between the low and the high marks. My no-spill funnel does not go right down and fit snuggly into the filler next on the rad ..it kinda stops a bit short of that, so that is what is allowing the expanding coolant, once it rises up in the funnel, to slowly drain back down the overflow hose and into the overflow tank. At one point when I did the first burp, all the coolant drained off in the “coolant reservoir” (as the owners manual calls it). The only reason I pinched off the small rubber hose that goes from just below the rad cap and over to the overflow tank was to allow coolant to build up in the funnel so I could observe any air bubbles escaping from the system. Given this more detailed explanation, do still recommend that I do the procedure again??
(2) Thanks for confirming my method of not running the blower motor during the burping process …made sense to me from the outset.
(3) As I have stated before, BOTH upper and lower heater core hoses get hot (a little to hot to hold onto) during the burping process, and after a highway run they remain fairly warm.
DJDEVON3: Thanks for the shots from the 93-97 manual …however the setup on my 92 2.2 litre 4 cylinder engine is completely different: hose configurations are different; thermostat location is different (although it uses the same thermostat), etc., etc. I have both a 93 626 and a 97 626 …both with the V6 engine, and their setups are completely different than my 92
I have the Owner’s Manual for my 92, and it describes how to change the coolant. There is no mention of a bleeder valve. It says that after the old coolant is drained, to add new coolant, and then “run the engine at idle with the rad cap off; slowly add more coolant as necessary; wait til the engine reaches normal operating temp; depress the accelerator 2 or 3 times; add more coolant if necessary until the system is full; install the rad cap; inspect the coolant leve in the coolant reservoir.” That’s quoting directly from the Owners Manual …seems to me to be describing a “burping” process.
Yesterday, I ordered a CD version of the 88-92 Shop Manual off Ebay …but it won’t be here for a week or ten days (or more).
Thankfully, the ambient temp here has been in the -5C to +5C range for the past several days …which has allowed me to work on the car outdoors. However, the forecast is for things to cool off considerably in the next while, so you can understand why I’m anxious to get this sorted out ASAP.
Oh good lord I forgot that your car is a 1991 there for a second sorry, my fault. I’ll delete all of that junk since it just makes this topic unecessarily longer my apologies. I have a 1988 factory manual on the way but mine is the real deal paperback. Will be interesting to see if there are differences between your digital version and my paperback.
If the hoses going into the heater core also get cool when you are loosing heat then perhaps there is a thermostat issue. I honestly don’t remember if you said you replaced it or not but I have known some aftermarket units to be a problem, it could also be that something got lodged in it causing it to hang open. The key is to find out if the problem is the result of the blend door in the HVAC or some other air delivery problem OR if it’s an issue with the cooling system, based on your most recent description I would say you’re probably looking at an issue with the cooling system possibly with temperature control.
If one of the coolant passages became clogged, i would ‘assume’ you would have external leaks due to the lack of coolant circulation and pressure build up as well as over heating issues. Also if you tried to flush the system, there wouldn’t be much if any coolant exiting the block if that makes sense going by your broken impeller statement?
Quoted From djdevon3:
This is the cooling section from the 93-97 626 manual.
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http://i306.photobucket.com/albums/nn24 … /E1-14.jpgIf you can find something useful in the manual go for it. This is above my head. I have absolutely no idea why he’s not getting heat. The 626 has bypass hoses so that coolant still circulates even if the thermostat hasn’t opened up. I imagine most engines has a similar design to help the car warm up during winter faster. His thermostat is obviously working right otherwise the heat wouldn’t disappear so fast while driving. Coolant temp sensor I believe he’s replaced. Sounds like for whatever reason that the engine isn’t able to produce enough heat to offset the -30F ambient temp while driving. I’m in FL so have no idea what’s that is like or what would cause that. Hope you get this fixed bro. -30F ain’t no joke.
The 93 and up 626’s are nothing like the 92 and down.
He did test the thermostat with a microwave and thermometer and it operated to specs. After something happened he decided to test the new thermostat. I believe he tested the original and a replacement and came to the conculsion that both were working correctly so he returned the new one.
Just a general question here that I don’t think I’ve ever seen answered. How would you go about diagnosing a clog in one of the engine passages? Say a broken water pump fin just for the sake of argument. Is there a coolant pressure test that can be done? I’ve seen you hook up a vacuum pump and use that to add pressure to find the leak near the radiator cap in one. Would that be a suggestion maybe digger can follow up on if removing the dash comes up with nothing?
Hi Digger89L,
From the descriptions and various tests performed, it appears that the inlet and outlet hoses to the heater core get hot after the vehicle has been operated for some time. Also, once the heater core hoses get hot, there is a short blast of hot air when heat is demanded from inside the cabin, followed by a decrease in cabin supplied air temperature, resulting in luke-warm air (at best) being supplied inside the vehicle’s cabin.
A couple quick suggestions to try (if not tried already):
1. With the car warmed up, and with the heat “on” inside the vehicle, massage (squeeze) the inlet hose to the heater core. Wear protective gloves, as the inlet heater core hose and surroundings will be hot. Listen and feel for any spongy-ness that could be a sign of air in the system. After squeezing the inlet hose multiple times, see if there is any increase in the hot air being supplied inside the cabin of the vehicle.2. If the above does not yield anything, check to make sure nothing has become trapped inside the HVAC system. A blocked duct (plastic bag, leaves, etc) in the HVAC will act to starve the system and prevent proper air flow. The blower fan might be working just fine, but unable to move the air properly due to a blockage in the HVAC system.
3. Verify that the heater control cable works properly. I was not sure from your earlier post whether or not you were able to confirm this or not. If any cable wire is clamped, confirm that the cable is properly clamped in the correct position. A friction-type clamp fitting could loosen up, and allow the cable to move but not activate the proper blend door lever. Thus, the lever attached to the cable “appears” to work, but in actuality, the cable is not moving the blend door properly.
Good luck and keep us posted.
Thanks for the additional info, guys. Especially that Service Manual scans, djdevon3! There was some helpful info there.
BRIEF UPDATE to answer some of the issues / questions raised since my last post.
Eric: I understand from the scans from the service manual that the lower heater core hose is the IN hose, and the upper hose is the OUT hose. I have never had an issue with the lower hose heating up …but just yesterday after a 25 mile run (and no heat!!) I checked the hoses, and the lower was hot …but the upper one was COLD! This is a new situation, as previously both would get at least hot to the touch. Now perhaps there’s been some crud moving around in the system, and the heater core is plugged (again?). The thermostat in the engine NOW is a new, single-stage unit (I tested it). I also tested the thermostat I took out (a dual stage unit) and it was working fine as well. I’m keeping it for a spare. The system seems to be getting LOTS of air (hence the cold air situation) …and I’ve checked( as best I can) the cable controls to the blend door, etc. and all seems to be in order. My car has the strictly MANUAL controls, so there are no electronic issues to be concerned about.
dreamer2355: no leaks in the cooling system. Can’t swear by the water pump being 100% …but there’s no evidence of it not working properly. When I did the funnel-air burp routine, the coolant seemed to be flowing fine.
djdevon3: Thanks again for the scans. I have a digital manual coming in the mail (soon, I hope) and I’ll find a way to get that posted so everyone on the forum can access it. I know what a pain it is to be scanning stuff.
BigC: Your summary of the situation is basically correct, except that now I have a “cold” heater core outlet hose (top) situation. Point #1: I’ve done the hose massaging routine each time I did an “air burp” and it hasn’t made any difference to the cabin heat. Point #2: Short of taking the entire HVAC system apart, I have checked for evidence of blockages, etc. However, I have ruled that out, as there is plenty of air flowing through the system, and when I change the settings for where the air is supposed to flow, it changes as required, without any noticeable change in air volume. Point #3: Again, short of removing the entire dash to have complete and clear access to the HVAC system, and where the cables connect to the underdash works (especially directly behind the control unit) I have checked the operation of the cables and the gizmos as they move on the heater box, and they seem to functioning properly.
I now have access to an indoors, heated work space!!! Its -14C (+7F) outside today, so taking this troubleshooting process indoors is going to make things a lot more pleasant ….and hopefully I can make some significant progress today. My plan for the day is: drain the coolant (again!!); replace the upper and lower main rad hoses (picked up new ones the other day, as the existing ones “may” be shedding material from the inside and this may be the source of my heater core blockage); clean the heater core with some of that same chemical in the slim grey jug that Eric used in his demo video (I think its initials are CLR); check to see that the thermostat is not being held open or closed by some kind of crud.
I’ll report progress, if any.
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