The service manual does say that the compressor is on during Floor/Defrost and Defrost modes, and when the A/C button is depressed. However, the owner's manual states that putting the ATC in defrost mode is full manual override, and that the A/C button must be depressed to get cooling (it doesn't say you have to depress it in defrost, but it doesn't say you don't need to either.) I am going to try it tomorrow, and see if the compressor comes on in manual defrost mode.
Dick
OK. Here's the scoop. The A/C does NOT turn on in either the manual Defrost position or the Defrost/Floor position. It DOES turn on in the two right positions, Bi-Level and Panel. So the only way to have the A/C on in defrost mode is to push the A/C button. This is on a '93 JGC with the Automatic Temperature Control. Same as the OP. I have owned this Jeep since it was new.
Dick
Okay, but if that feature is broken/defeated, but the AC can be manually turned on, then manually turn it on and get on with life.
I can see where somebody might not know that turning the AC on in Defrost will remove fog on the inside of the glass, but searching for a service center to fix it when the AC has to be switched on manually is probably not a good use of perfectly fine money or time. Personally, I prefer the AC to NOT turn on automatically at any time. I like the air to be directed to various locations inside my car without regard to what other life support systems mught be engaged, or not engaged.
I would accept that operation and not seek out repairs, regardless of what the Owner's Manual says it should be doing. If I can set the Defrost, and depress the AC switch and the AC comes on as a result, and blows onto the glass, then I'm one happy guy.
When all else fails:
I broke down and read my owners manual. The information was not the section under Window Defroster as I expected but Window Defogging.
The defogger turns on the AC for the condenser to dry out the air going through. It does not 'turn on the AC' as you gents are taking about from the way I understand it and have seen.
If you open the hood and watch while you have it in 'defrost' or 'defog' mode, you will see the AC pump turn on. You will not get 'AC' or cold air unless you request it.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT'sBilly Ray wrote:
Dick did pass the time by typing:
That is correct. The AC button on 93ZJ with autoAC works just like the button does on my manual AC. You have to light the light to get the compressor to kick in.
It might _might_ be programmable via the DRB-II scantool since it, the computer, and the overhead console share the same buss. There are no faceplate programming options, just tests.
Well Mike, I just went out to prove you wrong, but you were right on. Even though the A/C "star" doesn't show in the digital window, the A/C compressor is indeed running when the switch is set to the manual defrost position. However, it is really a case of semantics. When the A/C compressor is running, the A/C is ON, no matter what you call it. There is only one system for cooling/drying air. The system will ALWAYS cool the air if the A/C compressor is running. It may be hot coming out of the defroster vents, but that's because the heater is heating the air after it is cooled. It must cool first to dry.
So bottom line. If you put the ATC system in manual Defrost mode, the A/C compressor will come on and cycle as needed. If the A/C compressor does not come on in manual Defrost mode, there is something wrong with the system, and the self diagnostics should be run on it.
Dick
:-)
That is why Billy Ray's manual mentions saving fuel by not leaving it in defog unless it's needed. Defog is now like running AC as far as mileage goes.
Mike
Dick wrote:
Thanks guys, Dick, Mike, Earl, Jeff, Lon, Billy Ray and others. I explained to the wifey how it should work and how if that fails she should try it (by manually selecting ac on). I'll put the system through its self test next chance I get and let you know what the results are.
Cheers and thanks again
Snow...
Robb,
When you get a chance can you send the pix of your Jeep?
OK Snow. If you do get some failure codes, I can look them up for you.
Dick
....preferably parked on your head ?
Dave Milne, Scotland '91 Grand Wagoneer, '99 TJ
You leave me speechless.
You are just too stupid for words....
Mike
"Robb S via CarKB.com" wrote:
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