I been reading post after post, faq after faq, search after search. Seem most post end with no conclusion to the problem.

Here's what I have:

92 f150 4.9L, bought it a couple of months ago knowing the ac wasn't working PO had it converted to 134, said it worked great until they put on the bodylift. Compressor clutch is working, I'm sure I have some blend door issues but I've bypassed the heater for now.

ac on max, outside temp 85*, engine off high/low at 100psi, engine at idle low 55psi high 125psi, center vent reads 93* When engine at apox. 1800-2000 rpm, low 35, high 180, center vent reads 85*.

My guess is the compressor is worn out. Is there another way to test? If I do replace what else do I need to replace? I'm hoping there's something else I can do/check before replacing the compressor.

Thanks TBH

 

Where are you located? I know of a few places around here that could tell you.

 

It looks like you might be low on refrigerant, but the high Low side prssure makes me wonder if you also have air in the system.
Your pressures overall are a little low but you should notice "some" cooling.

Run the system at 1000-1500 rpm for about5 minutes then feel the evaporator tubes where they exit the firewall. They should both be cool (cold on a properly functioning system). Also record your pressures.

What kind of issues are you having with the blend door?

 

I'm in North Augusta, SC

I ran it for maybe 45-60 sec earlier but I'll do it for 5 min in the morning and post the numbers

I noticed that when I was running the vent only the temp coming from the vents was hot not as hot as with the temp. control on hot but a lot hotter than it was outside, so I bypassed it and it blows outside air temps now. I'll tackle that problem later. I want to get the ac cooling and the body lift off first.

Thanks for the responses, TBH

 

I had a few minutes so I hooked everything up and checked it out again. I wedged a clothes pin in the throttle stop this time and ran it at around 1500 rpms for 5-6 minutes. Right away I noticed the compressor started to cycle on and off. before it was always on. After 5 mins. temp 90*, low 25, high 110, center vent 88* . After a few more minutes the compressor stayed on, then I noticed the engine was overheating. The PO installed an electric fan when they installed the body lift. So then I got out the garden hose sprayed the condenser and the radiator cooled everything down and the compressor started cycling on/off again low 25 high 105. The evap. tubes were slightly cooler than the outside temp.

 

Great Info!

It sounds like you have a (very?) low system charge but it's being masked by poor condenser airflow.
You won't likely get the AC to work correctly until you uninstall the body lift or install much higher CFM cooling fans to remove heat from the condenser.

Your engine needs airflow to remove heat from the radiator. It's a lot of heat, but just about "any" airflow through the radiator will keep the engine from getting too hot.
However, the AC system needs LOTS of airflow, consistently, to cool the condenser and operate properly. Actually, much more than the engine does.

On totally stock trucks, the VERY first sign of a weak fan clutch is poor AC cooling at idle/low speeds. The engine won't even notice a failing fan clutch until it's almost totally dead .

Electric cooling fans in modified applications that will keep the engine perfectly happy won't necessarily make the AC system happy. It sounds like your cooling fans will cool the engine just fine but aren't robust enough to cool the AC condenser adequately.

Hope this helps.

 

Thanks for the info, I'll hit the junk yard in a few days and see if I can locate a stock fan and all the plastic, then I'll lower the body, recharge the system and see if that works. Thanks again for the input it was very helpful. TBH