I have an odd heater issue, at idle it blows cool then once running it blows hot.

I thought I was low on coolant, checked it and all is well. No issues.

Is there any type of diaphragm or anything that regulates coolant flow like on other vehicles?

 

do you mean that when engine is cold it blows cold and warmed up it blows warm? coz thats kinda how its supposed to be.

otherwise id check the heater hose on the firewall on the pass. side of the engine bay. prolly leaking.

do a search, there was a 1st gen w/similar problem a while ago.

 

Yeah obviously it blows hot when the motor is up to temp and blows cold when the motor is cold... do I come off that I would mistake that?

Reread my post before replying please.

There are no coolant leaks as stated.

 

...i did, i was clarifying what you meant so i could give you a more precise answer. which was the 2nd part of my post....

problem could also be the thermostat, to check, drive your car (from cold start) for ~10mins in moderate weather (obviously a lil longer where its cold) and check that the temperature gauge is in the middle between H and C. if it isnt means thermostats likely crapped out.

 

my car is doing the same thing also not fun when the high s are in the -15º F range

what could it be if the Thermosate isnt the problem? my temp guage is usally in the middle, when the car is moving adn on outside air its fine but when i slow down or come to a stop it blows cold air unless i put the heater on resurculate but i cant leave it on resurculate long because all the windows will fog up and then ice over.

 

check the heater valve right behind the throttle of the engine. top left almost near the middle of the engine. it can go bad and rot the cable that controls your heat.

 

TTT, still looking for an answer...

Thanks

 

I think you have a vacuum leak somewhere in the system. At low rpm the vacuum is not adequate to operate the vacuum servomotors that control the air blend.

 

Coolant seemed okay, I'll recheck.

I wasn't aware this was still a vac assisted system.

 

Mine has the exact same issue. When at a stop (even when the car is warmed up) the heater blows cold. Once it starts moving again the air gets hot.

 

Your heater control valve is vacuum operated. The valve is located on the firewall just behind and above the engine. You can see heater hoses to and from this valve as well as a control cable from the vacuum operator.

If you have a vacuum leak, this valve may stay closed at idle but open to the proper position when engine speed comes up. You can verify this by watching the valve while someone else revs the motor.

If this is the case, you will need to carefully inspect your vacuum system to find the leak. It's probably a cracked hose over a fitting.

Good luck.