A/C blowing hot with R-134a charge

[ranger hans]

I've got a 1988 Ranger with the 2.9 V6. My problem is that my A/C is blowing hot air, but there is a charge of R-134a in the system (it was converted many years ago and has worked on and off since).

The compressor was replaced about 3 years ago and I believe a few other components are new to system as well, circa 3 years ago. The compressor is turning (not just the flywheel, but the compressed clutch is engaging), but the air coming from the vents isn't getting cold. I know that freon is circulating because when I put a gauge on the low pressure side, it would jump from high to low as the compressor cut on.

My first thought is a bad expansion valve but wanted to run this by you guys to see if anyone else has had experience and wisdom to share.

 

[cvar]

What are your high & low side pressures? Ambient (outdoors) temperature too? And how often does the compressor cycle on & off?

Dropping low-side pressure when the compressor kicks in suggests that it's trying to draw r134a by suction, but it doesn't mean it's actually flowing as it should be, esp. if the orifice tube is blocked. And are you low on refrigerant?

 

[f3joel]

Might need to adjust air gap on the compressor clutch.

 

[adsm08]

You can't tell anything by the low side pressure alone, and just going by pressures isn't that accurate a way to say if the system is fully charged or not. You need to evacuate the system and see what is recovered.

Unless you have access to actual AC equipment air conditioner repairs are best left to a shop.

 

[kimcrwbr1]

The only way to know what is going on is by hooking up a set of guages. You can try adding refrigerant if it is cycling on and off rapidly that is normally the low pressure cutout.
Just use the delta temps inside. Put the A/C on max and measure the temp under the dash center mast and the air out temp. You want to see at least 20 degrees difference. Just add a little refrigerant first off and see if it starts to take longer between cycles. If not you need a set of guages to see if it is going high pressure on the liquid side. Was the work done to it done correct? was it pressure tested? Was it evacuated properly? If there was water in the system when the refrigerant was added you likely need a new compressor, orifice, suction line filter and a complete flush to remove any acid in the system.

 

[ranger hans]

Thank you all for the advice! Sounds like I may just need to take it to a shop. I don't have much by way of AC equipment at the house.