AC problem

i hava a 1995 jeep cherokee thats having ac problems. I just had the compressor changed cuz the original had busted on it..clutch had locked so i had a mechanic install a rebuilt compressor. Now the ac does hot cool enough like it used to b4. There were no leaks detected in the system..could it be the expansion valve? Any ideas would be greatly appreciated. Thank yall.

My first thought: is the system charged enough?

yes... system is charged according to mechanic.. i even took jeep to another tech and they checked the pressure and found it ok..

My next thought is the blend doors under the dash. The vacuum hoses can disconnect and/or go bad.

should i add half of a can of quick cool freeon to see if that helps??

That's what I would do. With the small cans it's unlikely you'll overpressurize the system.

still having problems with ac not cooling enough...compressor is new, filter and expansion valve is new, system is fully charged...any ideas anyone? this is getting frustrating b4 the ac worked fine with no problems..been trying to find those blend doors but cant get to them..any ideas or suggestions would be greatly appreciated!

I tend to agree with fredjacksonsan that your prob most likely is in the mixing doors, or possibly with the controls for them.

A couple things come to mind.

1. have you checked the exit air temp from the ducts? It should be in the 50's if the system is working properly, (it takes a few minutes to reach that temp, have patience!) but only if the doors are aligned correctly for system recirculating. If the doors are aligned for outside air, then you will be mixing hot air with the cold. Is your fan moving the same amount of air it was prior to your having the A/C "fixed"?

2. if you turn off the compressor, and at the same time call for some warm air through the dash vents, does the air get hot without turning the temperature dial up? If so, I'd probably suspect a blending door problem, or it's possible that something got knocked loose under your dash, during servicing. The small tubing that transmits the vacuum signals to the doors can go bad, fall off etc. Recommend you grab a flashlight and get under your dash. You might even find that your cold air is going through the window defroster ducts. I think if you'll spend some time looking it over, you'll find your prob. Good luck.

Bob

still having problems with ac..looked under dash and all the vacuum hoses seem to be ok...there are 3 vacuum motors under dash beneath the steering wheel..those look in working order..i still cant find the one that controls the actual blend doors, any ideas where this should be? How can i get to those blend doors..im willing to check the problem myself if i had some diagrams on how to get to them..any ideas would help..thank you guys !

I just went out and looked at mine (a 97). It looks like there is one temperature blend door, and it's controlled by a small stainless cable from the temperature knob. You should be able to see the cable at the extreme top right side of your transmission hump, and you should also be able to watch it move as you turn the temp knob from cold to hot. If, as you rotate the temp knob, the cable end doesn't move, then I'd guess that it's come loose from the anchor point on the temp knob. If it does move in and out, and you can't hear the door moving, then possibly the anchor point is broken off your door lever arm, or the door itself has come loose. This is my first "civilized" Jeep (with A/C) so I know little about A/C quirks with them, BUT, blend doors falling out is a fairly common problem with Fords, and a real PITA to fix.
Looking in my service manual shows that Cherokees also use an A/C thermostat, mounted inside the blower housing. From what I could tell in the book, if it was that thermostat causing your problem, I think I'd look into scrap prices for junk Cherokees, although there must be a trick for doing the job at flat rate speed. Are you on good terms with any of your local dealers wrenches? Pulling dashboards for working beneath is high dollar stuff. Sorry, but I have no good news!
Hope this helps.
Bob

yeah..i had looked at that cable you say and im thinking that could be the problem but still i would have to lower the dash to get to that blend door..and that thermostat, i hadnt thought of that... do you think it could be the the controls itself..when i move the control to cold the thing wont go all the way i had read that there is a vacuum hose conected behind.. I dont know what to do with this problem anymore..spent lots of cash and for the thing not to work properly..that really sucks thanx anyways for the pointers..ill let yall know how it went.. cheers!

Ask the mechanic that repaired it how much vacuum he placed on the system prior to charging? You are suppose to vacuum the system down to less then 1000 microns or equal to 29" of vacuum. If there is non-condenseables in the system you will get a low exchange rate. The mechanic should be able to fix it correctly and obtain a temp that you are comfortable with (or 40-45 df from the vent). The R134a charge should be in the ballpark of 40 psi on the suction side.

hey... i found a little bent on the high side line that goes inside to the dash..it is where it connects to the expansion valve..looks like the guys tried to hold the line with some pliers to try to connect the nut to the expansion valve..could that be the cause of the problem anyone? the line is not bent all the way just from one side it is flat.. any ideas would be alot of help...thanx!

You stated that the initial problem was a locked up compressor? IF so then the shop you had service your AC should have known to flush out the condensor, evaporator, ALL lines and replace the expansion valve and accumulator(dryer). If this was not done, it could be the root of your problem. Also how much oil did they use, should be about 2 oz in a dry compressor with about 2-3 added to the system while charging, I think the dryer sould hold about 5 oz. If this wasn't done and you have a lot of crude from a failed compressor in your system, you won't get the performance from it like it was before.

im thinking bout taking it to the shop and get the whole system re-vacuumed and recharged to see if that helps with anything...really getting sick and tired of this problem...the hot summer heat down here is hell without a good a/c...will keep yall posted....thanx

maybe too much oil is in the system

I think you might still have crud in the system. Hillbilly Ac check is in order... Put the ac on max, recirc mode, full cold and let it idle a few minutes. The low pressure line from the evap to the compressor should be ice cold and sweaty on a warm day all the way to the compressor fitting. This is the larger line. If it's not, your low on refrigerant. The line from the compressor to the condensor by the rad is the high press side and it gets hot so be careful. The only area that should be cold it the expansion valve to the low side hose at the compressor. If any other components have a cold spot, you've found your restriction.

Yes, too much oil (or air in the system) will reduce cooling ability too but your low side hose temp will be consistant. Any moisture can freeze in the receiver/drier and cause blockage their. You can usually feel it there though.