A/C Concern: not blowing cold

[BlueStang73]

Just had a quick HVAC question. ive got a 97 gt and i'm having problems with my a/c not blowing cold. checked pressure lowside/high side (good). system is charged to spec. compressor kicks on both norm. a/c and max a/c. mix door can be heard. mix control has resistance when moving to cold selection and pulls towards the hot side. i've also noticed the compressor cycling more often than normal. right off the bat im thinking cycling switch. has anyone run into this already? i'm a GM tech so i'm not familiar if ford's switches go out as often...any help is appreciated

 

[bhuff30]

If the pressures really are normal and where they should be, a pressure switch may be to blame. They do occasionally fail, but I think more often they fail and prevent the AC from running at all, instead of reading an incorrect pressure and causing cycling.
There are 2 switches, a high side switch and a low side switch.

 

[Mike97gt]

The low side switch controls the cycling..

So yeah if the system is charged to the correct capacity and it's still short cycling then I would think the low side switch is bad..

You can jump the pins on the low side switch and see if it blows cold.. Just do that long enough to see if it gets cold..


If it's not the cycling switch check the orifice tube.

 

[BlueStang73]

i jumped the low side switch to run it constantly and it engages just dosen't blow cold

 

[omar2000]

An A/C cooling problem is best done by connecting a gauge set to the low and high pressure service fitting on the system. Though poor cooling is often due to a low charge of refrigerant, it can also be caused by many other factors.

 

[wmburns]

Hopefully this does not come across wrong, but something doesn't add up.

Let's cover some basics. Confirm that the engine cooling fan come on when the AC is turned on.

Confirm that the inside vent fan works.

Confirm that the heater works when the mixing control is turned to HEAT.

When in the VENT mode, does the air blow through the vents?

Confirm that the AC compressor runs when the low pressure switch is jumped.

Confirm if the AC suction line at the receiver dryer gets a "sweat back" condensation. If not, the suction pressure is not low enough for proper cooling. The challenge is to find out why.

Please post the high/low side pressure readings. It just doesn't make sense that the Freon charge is correct. Reason? If the low pressure switch is the problem, then jumping the low pressure switch would restore function. It doesn't.

SO...there has to be other issues going on.

Therefore, IF the pressures are good AND both fans are working, THEN the only reasonable option is there is no air flow over the evaporator core.

Or the blend door is mixing heat with the AC so much so that it appears the AC is not working.

My gut is the AC system is not fully charged and there is a problem with the vent/blending damper.

For verification, please consider that if there is a blockage in the AC lines, this will show up in the pressure readings. This is why I want the actual readings posted. Will also need the outside and inside air temperatures.