pushnf8

Ok, so my a/c is blowing hot air. I have found the source of the leak and repaired it. I then purchased a "home" recharge kit. My problem is that after charging the system to 34 oz I still have no cold air. The guage on the recharge kit fluctuates when the system is running also. Indicates system is charged but the sec the compressor kicks on the guage bottoms out. It also feels to me like the top line (high pressure?) is VERY hot to the touch where as the lower line is normal temp. When I took the lower line off the front I cleaned the little screen that was located inside of it. Im not 100% it was put back in the correct way (any idea if it is directional?). Im wondering if anyone has an idea as to what could be wrong or if Im missing something. System accepted the charge, compressor is kicking on (although short cycles about every 5 seconds), all fuses and relays appear fine. Im thinking the line is blocked somewhere. Not sure if its in the evaporator, condensor, ???. Anyone have any insight? (04 f150 scab. 5.4l)

ford4wd08

are you recharging it with the truck on and the AC on full blast? it has to do that to suck in the line low pressure side. and the lines usually have condensasion around them from being really cold.

GATORB8

Bad pressure sensor maybe, it may not be getting cold on the low side because the fan's not pulling.

pushnf8

Truck is running with a/c on max air when I charged it. I found that if I shut the a/c off for a few minutes then turn it on full blast it blows cold air for a sec then right to hot air. Almost seems like there is a sensor or protection device tripping it to save it? Is there a reset button? Was thinking of disconnecting the battery to potentially reset any stored code or saftey switch but need to confirm it wont cause any other damage to truck (computer, door button codes, remote start, etc...) Any input on that? If I jump the sensors on the high and low pressure lines would that tell me anything? No clue with this stuff and looking to save money from the dealer. would appreciate any info or operation schematics.

RahX

You have to vac the system anytime you open it up to remove the air. The A/C system does not operate on atmoshpereic gasses. As far as pressures go, 30 on the low side running should be a decent number to see. 200ish on the high side is a good number as well. If it is bottoming out on either side, that means there is TOO much of a restriction. You are probably in the territory where you need to have someone look at it.

Mod (Ret.)

X2 on the vac proceedure. If the A/C system was low/empty of freon for a period of time (longer than a week), the dryer needs to be replaced as well.

philbosaurusrex

I can't offer much advice on the refrigerant aspect, but I can tell you about a common AC problem on all of our 04-08 work F150's. There is a mixing valve in the duct work that blends hot and cold air under the dash. There is an electric motor which controls the mixing valve (it may be vacuum actuated on some models) that malfunctions and gets stuck with the hot air wide open. If all of the components in your AC check out, and its still blowing hot air, then the mixing valve or the electronics in the control dial is probably the culprit.

I diagnosed this problem in the following way; start the truck in the morning with the engine cold and turn the AC on full blast. Keep and eye on the temp gauge, and keep your hand over a vent. If the temp of the air coming from the vents gets hotter with the engine temp gauge, then the mixing valve is stuck blowing hot air. Unfortunately, it's a $500+ fix at the dealerships. The (sort of) good news is, you can buy a replacement mixing valve motor for $250 and replace it on your own. You have to take out the radio and climate controls to get enough access to change the parts under the dash. I hope this helps.

djjr50

Maybe this is the answer to my issue. The price on that hurts. I will hope and pray that my truck is still under the bumper-to-bumper warranty so I dont have to foot the bill. I have only had this truck 2 weeks!