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Hi,
I am pretty decent with cars but I have an annoying problem. I have a 2000 Intrepid, 3.2L with about 162,000 miles on it. I have put a new water pump, new radiator (original one leaked on the pass side tank), new thermostat and new hoses on the car. Not too long ago, my ATC control head (the original one) went bad (the LED lights went on it), so I bought a refurbished one on e-Bay back in Dec. 15′ for about 80 bucks. It was working fine up until recently. Originally, I did the self diagnostics on it and a code for the mode door came up and it made sense because the air wasn’t blowing where it was supposed to so I replaced it. That worked great! This is my main problem now…I have heat coming out of the vents but I LOSE the heat at highway speeds during the cold weather! The colder it is, the worse it gets. Also, the temperature gauge needle goes all the way down close to the C mark. As soon as I get off of the highway, it goes back up! The heat is also not as hot as it used to be. It used to get VERY hot…not anymore. 🙁 I brought it to my trusted mechanic, and he bled the cooling system out, hoping that would fix the problem but unfortunately, it didn’t. At this point, I tried the self diagnostics, one more time and I got a code 36 which is ATC communication failure. I didn’t get a code for the blend door actuator. The guy who sold it to me told me that he would give me a new one with no problem. I don’t want to just do that if it isn’t broken. Is there anything else that it could be? BTW…I have the original shop manual on my computer but it doesn’t list this particular problem. If anyone could help, it would be much appreciated! Thanks in advance!
Rawson
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If you have access to a scanner with live data, I would take it on the highway and watch the coolant temperature. If that matches your gauge setting, it sort of sounds like a stuck open thermostat (even thought you changed it already), or coolant is getting around the thermostat somehow.
[quote=”Hotrodd100″ post=185339]Hi,
I have heat coming out of the vents but I LOSE the heat at highway speeds during the cold weather! The colder it is, the worse it gets. Also, the temperature gauge needle goes all the way down close to the C mark. As soon as I get off of the highway, it goes back up! The heat is also not as hot as it used to be. It used to get VERY hot…not anymore. [/quote]In the absence of any coolant loss …..
That is typical of a stuck at least partially open thermostat.
Instead of opening and closing to maintain the coolant at 195 degrees (or whatever T stat spec is) the thermostat stays open, allowing the airflow over the radiator to cool the coolant down to lower than normal temperatures.
The faster you go, the more air and coolant flow through the radiator.
The colder the coolant is the less heat you get.I do actually have an Innova scanner for OBD 1 & 2. It also has the feature to look at live data. I will definitely try that tomorrow. Thanks for the advice. 🙂
Thanks for responding. As far I can tell, there is no coolant loss. I have checked it several times over the course of about 2 weeks or so and it seems fine. Fortunately, no signs of any kind of leak – internal or external. 🙂
O.K. – Thanks to you as well for responding. I will definitely put a new one in and see how it goes. 🙂
Before replacing, inspect it; if it’s not completely stuck open, put it in hot water and boil it while monitoring the temperature, and see when it opens.
O.K. – Will do. One more question if you don’t mind. What about the code 36 on the ATC control head (Communication failure). It seemed to be working fine because I had some heat while driving around town and it worked when I tested the A/C out. Maybe I shouldn’t have done this, but I disconnected the negative battery terminal to clear the code. I did this over 2 wks ago (maybe even 3). I’ve checked it several times and the code hasn’t returned. How long does it take for this car’s computer go through it’s cycle? Also, do you think the control head is o.k.? Thanks again. 🙂
[quote=”Hotrodd100″ post=185370]What about the code 36 on the ATC control head (Communication failure). It seemed to be working fine because I had some heat while driving around town and it worked when I tested the A/C out. Maybe I shouldn’t have done this, but I disconnected the negative battery terminal to clear the code. I did this over 2 wks ago (maybe even 3). I’ve checked it several times and the code hasn’t returned. How long does it take for this car’s computer go through it’s cycle? Also, do you think the control head is o.k.? Thanks again. :-)[/quote]
If the code returns, deal with it at that time.
Hi,
Just wanted to let you know that I spoke to my mechanic on Friday (3/17) and I asked him about the code 36 (communication failure) just to verify it and so I know exactly what’s going on. Of course, he has a DRB III scan tool and he said that the code IS still there. He definitely feels that there is something going on with the control head. I had notified the seller of the unit a while back when I first experienced the code. I just let him know yesterday (Sat) and he is more than happy to send me a replacement. I just have to send the one in the car back to him. He’s shipping it out Monday morning, so hopefully I will get it in a few days. I have heard that sometimes the code 36 (comm failure) is a “boy who cried wolf” code but I’d rather not take any chances, and just put a new (refurb) one in.I will keep you guys posted as to what’s going on. 🙂Rawson
It’s great that the seller is such an honorable person and that would address the code issue with the control head BUT I can’t see how it will have any effect on this issue, as stated in your first post:
[quote=”Hotrodd100″ post=185339] Also, the temperature gauge needle goes all the way down close to the C mark.[/quote]
The engine coolant temperature isn’t controlled by the control head.
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Hey Everyone,
I just wanted to thank all of you guys again for all of your help and advice. The problem is fixed! The thermostat WAS the problem! I bought the OEM thermo and new gasket, put them in, put the coolant back in and then bled the system. The car warms up fast and great now, temperature gauge is exactly where it should be and I get AWESOME heat again even on the highway. Tested it last night cruising at 60 mph and it worked great! And believe you me, it was freezing last night. I also received the replacement ATC head and installed it today (Thu 3/23). It’s also good – double checked it for codes and all is well. Thanks again to everyone! 🙂
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