BraveHelios

Well it finally warmed up a bit here in Boise. I had my car sitting in my parents garage since it's really hard to drive the thing when there is basically any snow on the roads and we had a bunch of it for many weeks. Also; my parents do the snowbird thing so their driveway does not get shoveled... hence the car sat in the garage for almost 2 months. It's also been very cold for around the same amount of time. Since the time the temps have stayed in the 20's and 30's, the car has had no heat coming out of the HVAC system (another reason not to drive it). Now, within the last few days or so, the temps have been in the 40's and 50's and low and behold; I have heat again! I am trying to figure out if there is an association between the colder temps and no heat and warmer temps and now heat. At one point, I was thinking the coolant heater valve was the culprit and went and purchased one although I have not yet installed it.

Is there something else besides the heater valve that I should be investigating, especially with the newest evidence? Perhaps some sensor?

As always; any assistance is greatly appreciated!

FormerE30Owner

If you are talking about getting heat as the car warms up at idle (you mentioned that you could not drive it), then it is quite possible that you did not wait long enough for the car to warm up. When it is extremely cold, it takes a very long time before the coolant management system will give heat to the cabin if the engine is only idling - it wants to heat the engine up as quickly as possible and keeps the heat for the engine not the cabin. That might explain why you did get heat when the temperatures warmed up. The sooner you move off after starting the engine the better and you will find that the cabin temperature will follow much sooner than at idle. That is my experience, although at truly cold temperatures like 0 F and lower (I don't call 20s and 30s as very cold, btw, but then I am Canadian

BraveHelios

Thanks for the reply. There was a time; before the snows came, where it got cool (cold for me... the temps were in the 40's, then 30's, then 20's) and where I was still able to drive the car... got it fully warmed up (that's what the temp ring around the tach was showing me anyway) and yet I had no heat. I don't know if the warmer temps and the working heat is a red herring... if it means that something other than the heater valve is at fault.

BraveHelios

Bump... please:

any other tips?

DanielFD

If you already bought the heater valve, I'd replace that and at the same time remove the aux pump and hardwire 12v power from a battery to it see if it runs. If the heater valve has been damaged long enough it will probably burn out the aux pump as well. The pump is right under the heater valve towards the front of the car attached to the chassis. The heater valve part number has been changed a couple of times and its a known weak point, I'd buy that from the dealer. The AUX pump get from a breakers yard. Its not worth the 100$+ you would pay for it new.

seanjordan20

What prevents you from getting heat: Heater valve, thermostat, blend doors, IHKA and AUX pump. Either one of these can be your issue. Do you have INPA. If so you can test most of them and find what your issue is or at least find a code.

How hot is it getting when the temp is up? When was the last time you changed your thermo. You could of tested the heater valve by hand. The hoses temp will let you know if its working but if the thermo is bad you will not be able to tell. If the hoses are indeed hot then you know your thermo is good and the valve. You will then look at your IHKA or blend doors. I think I have the mapping right if not those are the things that can prevent heat.

BraveHelios

I will check what you recommend when I get home from work. Right now, it is 40 degrees out and overcast. Car is fully warmed up. Heat temp is cranked up for both dides and what I find is the drivers side center and side vents are blowing Luke warm, the passenger side vents are blowing cold. Does that narrow things done any? Yesterday was 5-10 degrees warmer and I had lots of heat!

BraveHelios

Update... I've been busy and it's been too cold (for me) to work on the car, so I drive it with barely any heat coming in.

I did notice something new though... it appears that when the car is warmed up and driven at speed (30 mph and higher) even if it is cold outside, warm air does flow through the drivers side vents (only) but if I slow down or sit at a stop light, the heat quickly goes away from the drivers side vents.

Any tips here that might narrow down the possible culprits to this issue?

If I did not mention this before... the t-stat, water pump and hoses were replaced around 4 years ago at around 75k. Car now has 100k.

Jim165

Having the same prob after cooling system component replacement. Actually heat started going on the fritz just before thermostat failure and thought that was the problem. After replacing the water pump, some hoses, the recocery tank and thermostat and all new coolant, I only had middling heat when either facing up a hill or moving. For me, it looks like a combo of air still being in the system and a failing/failed aux pump (which pumps coolant thru heater core) and heater valve. Indy quoted me $500 parts and labor.

Try burping the system:

- have the car facing up a step incline or jack up front.
-car must be cold. Unscrew the coolant tank lid
-turn ignition to "on". Don't start car
- turn all heat controls to full hot and fan on lowest speed and allow to run for 5 minutes. You can go to the drivers side of the engine bay and try to hear if the aux pump is running. It's right behind and beneath the air box. If not, could be your problem.
-now start car and allow to run for 5-10 minutes, cap still off coolant tank
-add coolant if necessary and drive for at least 30 minutes with heat controls still on full hot.

if still no heat, it's probably a failed heater valve and/or aux pump. Since you're getting heat on one side, you could be having blend door problems as well, as was mentioned.

seanjordan20

Do your cars not have an electric pump. It's a self bleed system all you have to do is initiate it.