08 edge a/c

[B dub]

I have a 08 edge and ac was blowing warm air sporadically and was weak took it to dealership and they said nothing wrong. Did some research and cleaned filter and added freon and now blows strong. But its still blowing warm. Mornings it's cold but afternoon is warm air with little hints of cold. Engine seems to be running hot and fan seems louder then usual and stays on few seconds after car shuts off...any thoughts?

[Dingo]

Compressor...

[autom8r]

Dirty condenser coil and possibly radiator.

 

What did the service ticket say the pressures were?

[B dub]

Didn't list pressure levels...just listed as "pressure-ok & blowing 40 degree". When parked in shade it's cold but warm when parked in sun and doesn't cool off.

[autom8r]

B dub,

 

It's never a short answer. For you perusal, here are my thoughts on your dilemma.

 

You mention "Engine seems to be running hot". Is your engine overheating?. Use an OBD-II reader to give you the operating temperature of the engine. Auto-zone will let you borrow theirs for free. If you are throwing codes like P0217, P1285, P1299 etc., the PCM will automatically lock out the A/C. Look for an obstruction blocking airflow through the condenser/radiator.

An A/C pressure transducer measures the refrigerant pressure and feeds this information to the PCM. If the pressures are too high or too low the PCM will lock out the compressor. These pressures will vary dependent on the cleanliness of the evaporator and condenser heat exchangers. If these surfaces are dirty or plugged with debris, they become inefficient and raise the pressure of the system (dirty condenser) or lower the pressure (dirty evaporator). A failing A/C pressure transducer may also cause intermittent operation. Bear in mind that when you add refrigerant, you may also increase the pressure of the system and risk slugging the compressor with liquid, leading to a seizure.

You mention that you "Did some research and cleaned filter". Was the filter really dirty? If may be that the filter allowed some of the dirt to pass through and clog your evaporator, affecting the system pressure. Mine was filthy when I first replaced it. Now I check it every other oil change. I bought the carbon activated filter as a replacement.

When I park in the sun, I've learned to close my BAMR cover and use a reflective windshield sunshade to keep the heat out of the car. The Edge is a voluminous car, with a tiny [undersized?] A/C system. It will take a while to extract all the heat from the vehicle's interior if you allow it to bake with all the glass radiating heat into the car. The refrigerant system only holds 21oz of R-134a, not even a liter of refrigerant!

The dealer may have allowed the engine to cool down and tested the A/C before the engine came to operating temperature [>205F]. In this case, the PCM would not have locked out the compressor. When you drove it home, the A/C worked until the engine temperature got too high and the compressor locked out. Then the fans came on, or you drove down an long shady hill and the coolant temperature dropped and the PCM allowed the compressor to come on. Then you went up hill, in the sun and the engine temperature went up and the PCM locked out the compressor again.

It may be any one of these things. I would look for overheating, dirty condenser first. That can be tested tonight using a drop light shining through the radiator from the engine side. Look through the grill and see how much light comes through. If you don't see any light, start there.

Good luck.