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Hi!
I’ve had issues with the heater in my car as long as I’ve owned it (two years). The heat isn’t good enough. The water pump is replaced (original part), the thermostat is replaced (original part), the valve is new (aftermarket part as original is discontinued). The valve is the one that control the flow, thus regulating the amount of heat. The engine is also at normal temperatures and the heater core have been flushed. The water flow through it without restriction.
In other cars I’ve driven the heat produced is so hot that it could be the birthplace of hell’s fire. In this car the heat is just lukewarm. It is not uncomfortable to hold my hand in front of the air vent over time, as it is in other cars. The temperature also drops if I have the fan at full speed. It also drops while idling.
This heater is without AC, and isn’t the type with vacuum control. It is a simple wire-operated heater. I’ve checked the wires, and they’re adjusted correctly.
I’m not sure if it is a coincidence, but it seems the heat output gets to normal levels if I drive with high RPM. Normal driving is slightly below 2000 RPM, while i got greater heat at 4000 and higher.
Any suggestions on this issue?
– Frank
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As another user has posted, your heater core. It doesn’t often work, but you could have your system flushed which would be better than tearing the whole car apart to replace the heater core, but if that does not solve your problem then unfortunately you’ll need a new core.
Edit, if your car is not over heating, the chances of a defective thermostat is slim, but possibly worth a shot.
I had a low heater output situation like described above. Bought a new thermostat and heated it and the one out of my car in a pan of water on the stove. The old thermostat opened before the new one did. The old thermostat had been in the car for some time and had previously provided good heat. Installed the new thermostat and heat was normal.
The first thing to check anytime you have a situation like that is for air in the cooling system. The heater core is the most likely place for the air to collect. More detailed info and videos in this article.
http://www.ericthecarguy.com/faq/solving-automotive-hvac-problems
Keep us updated on your findings.
As mentioned, the heater have been flushed and water flowed through it without restriction. I did replace the thermostat today. Bought a new one again, this time one that opens at 91 degrees Celsius. The old one opened at 82 degrees Celsius. I noticed a slight improvement on the temperature, but still not good enough. The temperature still vary with the RPM. Low temperature at idle, good hot temperature at 4-5000 RPM.
I’ll look up if there are any instructions on how to purge the system to get rid of trapped air. I had the car at a workshop just a week ago, so I would assume they’ve done it correctly. But again, I don’t really trust any workshop.
I’ll update again when I have removed any air that might be trapped.
Just to be sure… You said ‘Flushed’ which is not the same as a bleed.
Did you bleed the system?
Oh and replacing the heater core on a Volvo… I think I would rather have a root canal… I swear that Volvo starts the design of their cars with the heater core and build it around it…
The workshop disconnected the hoses and flushed the core clean. They told me it does not have any clogging inside, has good flow.
I checked my user manual and the system have been bled properly. Shouldn’t be any trapped air now.
Noticed something else, though. The aftermarket valve for the heater still restricts flow when fully open. Nothing is maladjusted, it is the design it self of the valve that is the problem. The original part (which is discontinued and cannot be bought anymore) is fully open and does not restrict. The aftermarket valve have a strange shape on the restricting plate inside the valve.
I would guess this design restrict the flow, thus causing lower temperatures. This is after all the valve that regulate the amount of heat.
I made a poor illustration of how the aftermarket valve looks like when fully open. The original part does not have this design, it is fully open when opened all the way.
[URL=http://s1218.photobucket.com/user/frankbilder/media/ventil_zpsae7a67a7.png.html][IMG]http://i1218.photobucket.com/albums/dd414/frankbilder/ventil_zpsae7a67a7.png[/IMG][/URL]
Aftermarket parts are often suspect. You might try taking it out of the circuit and just putting in a straight pipe. If you have good heat then, you know what the problem is.
Keep us posted.
I’ve now had the valve replaced with another aftermarket part. Couldn’t find an original part that didn’t leak. This new aftermarket part is made by another company, and doesn’t have that “figure eight” shape on the gate inside that restricts the flow.
The heat output is now as it should be, within 20 minutes I’m sweating inside the car. :cheer:
The other positive thing is that it doesn’t leak, as the previous valve did. Drying and washing out the leaked coolant wasn’t fun at all. Especially since I dried out the car a year ago after stopping a water leak.Heater output is insufficient and variable in the situation discussed is most likely either due to any defect in the thermostat or due to some abnormal activity such as distortion or partial blocking of the core. It needs a thorough inspection from every aspect in workshop for one or more problems those seems to be interconnected.Thanks
I’m having issues again now. Haven’t had the need to turn on the heat for almost 6 months now. On my way home this evening I turned the heat on again. After driving for 20 minutes it was still blowing cold air. I then drove for a short while with the RPM at 5000, and some heat started to come out. When I dropped the RPM down to around 2000, the heat went away and it blew cold again. Really strange… Is it possible that the engine it self has partial blocking? Blocked in a way that it doesn’t overheat, but also doesn’t provide hot coolant to the heater? The workshop said they flushed through the heater several times. There was no restriction in the water flow. For me it sounds like the engine it self is the problem.
Not sure if it is related, but when I’m driving to work in the morning, the engine temperature rises quickly. That is, the gauge in the dashboard rises quick. It goes from the bottom of the scale to instantly at optimal temperature after just 1 km or so, which is around half a mile. Never goes beyond that, just stay there at optimal. The coolant never boils over either, so it does not overheat.
The thermostat is brand new, changed out twice within the last year. The heat control valve is also new, almost 6 months old. Doesn’t leak. The water pump is 1,5 years old or so.
I’ve been a week offshore and have not been able to look into the issue before today. When I started the car after it have been sitting for a week, I noticed the engine temperature indicator were jumping up and down. This happened after it got warm. This led me to suspect that there was air pockets in the system. I opened the bonnet and were slightly puzzled, as the expansion tank still had correct level of coolant. The cooling system have also been pressure tested and bled 6 months ago and there were no leaks. I opened the cap carefully and raised the RPM, then all the cooland disappeared. I topped off maybe 1 liter (about 1 quart) of coolant, which is a lot. Everything is fine again now. Got the heat back and engine temperature is stable. Quite strange, how did that much air get into the system? As mentioned, no leaks.
Yea, everything you described sounds like air in the system. It’s imperative that the system be purged of air after any cooling system service to avoid these issues. If it happens again, check for air in the system. If you find air in the system the next step would be to find out what’s causing it. More info on that here.
http://www.ericthecarguy.com/faq/what-to-do-when-your-engine-overheats
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