Big67red

2004 Grand Cherokee Larado. The A/C is having several problems, and I am not sure if they are one problem or a few things all going out at the same time.
Symptoms: A/C works going first thing, then gets weaker after the jeep is driven for 10-20 miles. Blower cuts out when pulling away from a light or going up a hill. Air sometimes comes out random vents, floor, dash and defrost.
What we have tried so far: (forgive me for messing up the name of the parts) Changed the evaporator dryer(tubes/hose from the front of the jeep to the firewall w/ a cylinder and the evaporator (solid piece of metal that is next to the fire wall) Thinking was there was some dirt in the system and this was causing the system to mess up.
Whats next: After reading through many forms will check the vacuum lines next.
After that, any ideas?
Thanks, to add to the problems it is the girlfriends jeep, so I have not seen all the problems first hand, as of yet. I just get to fix them.
Thanks for all the help.

freegdr

Sounds like vacuum issue with vent changing issue check for line to vacuum canister issue .

SoCalxJ4.0

I had a issue in my 96 xj, doing the same thing. When the jeep was under heavy loads, the a/c would get really weak. All my vacuum lines in engine bay were good, I was about to pull the dash, when by chance, my arm hit the brake booster check valve line, and I heard a lot of air coming out! Went to Vatozone yesterday, picked up a new check valve, my a/c stays strong now. Cheap fix, and vacuum is back to normal. Check it out.

Big67red

Thanks for the info, will check this weekend. Tropical Storm permitting.

1SIC4X4

im kinda also having problems with my a.c. in my 95Xj. seems not to blow very cold when first running a.c. but drive for awhile and it gets cooler. figured it was low, but it was chk and its full.

cld someone plz post a photo of this so called check valve?

SoCalxJ4.0

The little circle with the "plus" in the middle on left side of booster.

Big67red

Still working on the problem. Other issue have come up that needed fixing first. The radiator went out and had to be replaced, and my Lightning needed, and still needs some TLC. So far we have found three cracked hoses, but the problem is still there. Check valve replacement is next.

Again thanks for all the help/ideas.

1SIC4X4

Can someone explain how this part could affect a/c?

I thought this was a brake booster..

justin13703

It's a vacuum line and vacuum is what dictates what vents the air blows out of...

1SIC4X4

Another logical answer please

Big67red

Still have not solved the problem. At this point the AC works, the cruise control is out, and the AC does change where it vents from.

Have changed most of the hoses on the driver side of the engine, a few looked like they may have been cracked. Changed the check valve on the brake booster, appeared okay, but did it anyway. The other check valve on that side appears to work fine.

Any ideas?

SoCalxJ4.0

The a/c heater switch panel?? If a nipple is broke on the back, that would be a vacuum leak.

mudshark99

I have similar problems with the AC in my 98 XJ. AC starts cold and gradually (10-20 minutes) warms up. If I let it sit for a few hours it blows cold again before warming up. AC does not change vent locations. Also cruise control used to work all the time. Now it rarely works. If changes to where the AC comes out is a symptom of a vaccum leak, and my AC comes out of the dash vents because that's where I set it, does that indicate my vaccum system is in good order? Also, is there a relationship between AC and cruise control? TIA.

Morat

Yes, there is. The AC vents and cruise control both use the vacuum system. If there's a leak/fault in the vac lines or reservoir then both you'll lose the ability to select different AC vents and cruise control will fail.

Muaddib420

Yours sounds like a worn clutch issue. Do this. It worked perfectly for me. No more cutting out when it's hot.