heat stops when letting off gas

[zrschaef]

so of course I have heat issues when its -3 outside. Here is my problem, it started a few days ago. When ever I let up off the gas pedal for longer than a few seconds, my heat starts blowing cold air. My heat blows nice and hot while driving though. My coolant level looks fine, and the coolant temp gauge does not vary, it stays where it normally does once its all warmed up. The amount of air out of the vents does not change, just the temp. Any help would be appreciated. Thank you.

edit:
I recently got my oil changed, if they checked my coolant level by taking off the radiator cap would that allow air in the system?

[fastblackmerc]

so of course I have heat issues when its -3 outside. Here is my problem, it started a few days ago. When ever I let up off the gas pedal for longer than a few seconds, my heat starts blowing cold air. My heat blows nice and hot while driving though. My coolant level looks fine, and the coolant temp gauge does not vary, it stays where it normally does once its all warmed up. The amount of air out of the vents does not change, just the temp. Any help would be appreciated. Thank you.

edit:
I recently got my oil changed, if they checked my coolant level by taking off the radiator cap would that allow air in the system?

I see two possibilities.

1 - Air in the system, burping the cooling system will fix it.

2 - EATC acting up or vacuum loss.

Yes, opening the radiator cap will allow air in the cooling system, but not enough to cause any problems. To check properly check the coolant, look at the side of the overflow bottle.

[marauderthis]

Exactly which cap was removed?
Was it the one on the plastic reservoir tank or the plug on the metal crossover tube? Which one???????

Were both removed?











so of course I have heat issues when its -3 outside. Here is my problem, it started a few days ago. When ever I let up off the gas pedal for longer than a few seconds, my heat starts blowing cold air. My heat blows nice and hot while driving though. My coolant level looks fine, and the coolant temp gauge does not vary, it stays where it normally does once its all warmed up. The amount of air out of the vents does not change, just the temp. Any help would be appreciated. Thank you.

edit:
I recently got my oil changed, if they checked my coolant level by taking off the radiator cap would that allow air in the system?

[RF Overlord]

I'm not so sure opening the reservoir cap will introduce air into the system. Technically it's called a "degas bottle" and is there to allow entrained air to escape from the coolant. Opening the system at any other point, such as removing a hose, will certainly allow air into the system.

[zrschaef]

Exactly which cap was removed?
Was it the one on the plastic reservoir tank or the plug on the metal crossover tube? Which one???????

Were both removed?

I am not sure. The tech just said they checked my coolant level and tested it and it was fine. Normally I change my own oil but its cold and I was lazy. The way its acting it just seems like air is in the system. Since the heat works perfect while pressing the gas. When I checked coolant level I looked at the side of the overflow bottle

[marauderthis]

I am assuming you have not had this car that long.
I strongly suggest you expand your knowledge and expertise very quickly.
If you dont get a handle on things preemptively or in a timely manner things will get very, very expensive.

[zrschaef]

I am assuming you have not had this car that long.
I strongly suggest you expand your knowledge and expertise very quickly.
If you dont get a handle on things preemptively or in a timely manner things will get very, very expensive.

you are correct. I just purchased this car in June. I've been trying to do my research on common problems. I'm very mechanically inclined and fully capable of taking care of the maintenance, what exactly do I need to get a handle on?

I was simply asking the question so I know where to start when I have time to look at it.

[Mr. Man]

Does it make a difference if it is in Auto mode or a specific vent mode?

[zrschaef]

Does it make a difference if it is in Auto mode or a specific vent mode?
it does not make a difference, it happens in automatic, vent, floor, etc.

[BLACKMARAUDER04]

My original HVAC unit only blows cold air.
I replaced it and had heat again.

[Fman]

Mine did the same thing just a few months ago...hot when the RPM's were up and cold when I slowed or stopped at a light. It was air in the cooling system. There are instructions somewhere on this site for proper burping procedure. I would try that first.