A/C blows Hot under acceleration 97 Explorer 5.0

[tomlando]

Hello

I have a 97 Explorer 5.0 that switches from A/C to heat when accelerating. The A/C system is fully charged and gets as low as 45 degrees at an idle. I am thinking there is a vacuum issue as is seems to be acting like the old vacuum driven windshield wipers. The air handler door may be going from recirculate to heat. Has anyone experienced this? Or can anyone give me some info on where and how to start checking for leaks?

Thank You.

UPDATE: I check the vacuum and it is fine. When I first got the vehicle 1 1/2 years ago the heater was bypassed. I put a new control valve and hooked it up this passed winter....and I guess that is the issue. I guess I will just bypass the heater core again....until next winter lol.

 

[Rick]

It could be the A/C vacuum check valve. Check this thread for info:

Possible Vacuum Leak

 

[2TimingTom]

Related?

I've noticed mine will go from vents to defrost under heavy acceleration. Once I get to the top of the hill, air starts blowing out of the vents again.

 

[SoHK_alumni]

Or, is it simply that under acceleration, the Wide Open Throttle relay is tripped by the PCM and turns off the A/C?

For sure, the vents toggling between vents and defrost under acceleration is from a vacuum issue but simply loosing A/C might be "as designed".

 

[L2rocku2]

My wifes 2000 EB 5.0 did this as well. Not good when you live outside of phoenix and it's the middle of summer Not to mention also having 2 small children at the time!!

In my case, it turned out to be the electric motor that controls the temp door/flap in the plenum. I did as the repair manual said and removed the steering column and dash to access the 3 screws. Turned out that the mrs had gone over some pretty rough RR tracks and right after that is when it would go from blowing ice cold to the devils breath when you accelerated. Took the old one apart and sure enough, it was missing 2-3 tiny teeth on one of the gears.

Actually had to change it out again just last fall. I went through the glove box this time Had one of my daughters get the very back screw in and started, then I finished it with 1/4 ratchet. Hope this helps & good luck

 

[tomlando]

Thank you everyone very much for the input.

I think L2rocku2 has the correct answer to my problem because the Temperature control knob has no effect on the temperature. It has been blowing hot even when I had it turned to cold using the vent. Are the replacement electric motors available? I am having trouble finding an ABS front wheel sensor that I sprayed with brake cleaner. My local Ford dealer said they don't make them anymore.

 

[albi1cnobi1]

Thank you everyone very much for the input.

I think L2rocku2 has the correct answer to my problem because the Temperature control knob has no effect on the temperature. It has been blowing hot even when I had it turned to cold using the vent. Are the replacement electric motors available? I am having trouble finding an ABS front wheel sensor that I sprayed with brake cleaner. My local Ford dealer said they don't make them anymore.

Not the motor separately, but as a unit yes. Stay away from Dorman(many horror stories) and try to find a Motorcraft unit. Available on Rockauto.com.

They usually come on a new unit bearing assembly so they are available. Rockauto.com has them, Part # 970022 $54.79 each. If you want the cheaper route, go to a junk yard and pull a couple of used ones.