Automotive Air Conditioning Information Forum (Archives)

benk on Mon August 19, 2013 1:10 PM

Year: 1995
Make: ford
Model: explorer

Anyone have any hints about this? My air conditioner works fine, but only for about 15-20 minutes or so. After that, it starts blowing warm air. But, if I open the throttle by accelerating fairly quickly the air conditioning starts blowing cold air again just fine. The cold air lasts a little while, then it starts to blow warmish air again, then I accelerate again and it blows cold again, etc. Could there be some sort of switch that I activate when opening up the throttle? I am not aware of one but am hoping for some sort of solution. It gets really hot in the car. Thanks!

webbch on Mon August 19, 2013 2:35 PM

Sounds like a cooling system problem to me. At a given engine load, the cooling temps stabilize with a constant A/C load. When you increase the throttle during acceleration, you provide more refrigerant flow via the compressor, but it takes some time for the engine temperature to rise accordingly. Hence the perceived improvement for short times when you accelerate.

You mention that you get 15-20 minutes of cool air initially, and then subsequent bursts of acceleration provide good cooling. Am I correct that those bursts of accleration provide improved cooling that lasts much less than 15-20 minutes after the initial period? That would support the idea of a cooling system problem.

low/high side pressures and temperatures should tell a more complete story.

Edited: Mon August 19, 2013 at 2:36 PM by webbch

benk on Mon August 19, 2013 8:32 PM

You are absolutely right. The cool air after accelerating lasts much less than the initial period of cool air. Are you thinking maybe a blockage, thermostat, or . . .? Thank you!

Leggie on Mon August 19, 2013 9:53 PM

How does it do when you're just rolling along on the freeway with minimal throttle input? If it responds to vehicle speed, suspect air flow over condenser (fan issues or dirty fins).
If you're finding compressor needs elevated RPM to cool, check the charge is correct. If you're seeing high low side pressure and low high pressure side,(i.e. 50/150 and temp is 95F) this is a symptom of deteriorated compressor.

webbch on Tue August 20, 2013 12:22 AM

Leggie's test is much better. Freeway speed should remove airflow issues from the equation. Cooling flow issues would show up as an engine overheating issue. low/high side pressures to diagnose A/C.

mk378 on Tue August 20, 2013 8:09 AM

Sounds like clutch gap to me. You rev up the engine, everything starts shaking differently, the clutch vibrates enough to pull in.

When it is not cooling, pull over and open the hood, check if the compressor is engaged. If it isn't, tap on the clutch plate with a suitable tool and see if that makes it pull in.

Edited: Tue August 20, 2013 at 8:10 AM by mk378

benk on Thu September 05, 2013 2:02 PM

Freeway speeds do not have an impact vs. surface streets. The situation is the same regardless of speed. It seems to be more of a timing thing. For what it's worth, the car runs cool, and never has a problem with overheating. I will check the clutch today as it is hot here and no doubt the a/c will stop working. Thank you all for the suggestions!

WyrTwister on Thu September 05, 2013 2:20 PM

This is a wild stab in the dark , but the thought occurred it may a vacuum or electrical control problem . Having to do with the correct dampers / doors being open and the correct dampers / doors being closed . Also the opening & closing of the coolant valve controlling flow to the heater core ?

God bless
Wyr