My aircondition compressor turn on for 3 second than stop than strat again for 3 second.. it this normal ?? or this us a indication of something wrong ? like low on freon ? do any one know where the aircompressor relay locate at ??

I get no cold air when the air condition is thanks

Thanks

Mine only cycles on and off like that when it is low on 'freon' (R134).

After reading the posts on this fine board, I checked the A/C on my 96 855T and found that it was also short-cycling. (This was at the same time that my check engine light came on for what turned out to be an unrelated vacuum leak.) Based on what I read here, I went to Walmart and purchased one can of 134a to try recharging my A/C. Just that one can, restored the A/C to more "normal" operation for only about $10.
Also, based on the other fine information on this site (and the $2k in repairs that I had in Sept. and Oct.) I took the car as quick as possible and traded it in on a Subaru Outback and eliminated the hemoraging from my checking account. I'll let someone else pay for the evaporator and vacuum hoses that likely needed replacement, as well as the loose front suspension.
It's too bad. The car was nice, but only if you can afford the endless, expensive breakdowns and upkeep.
Jim

If you're not getting any cold air with the a/c on and you're getting that compressor cycling, you're low or out of freon, and you may have a leak somewhere in the system (evap, compressor). Suggest you re-charge system, add dye, run it for about a week and then go look for your leak. Start with the dreaded evaporator.

FYI for anyone interested, I have been attempting to determine with 100% certainty if I have a leak because even though I am 99% sure I am not low on freon, I still have the tick-tock sound of the compressor relay pretty much every time I have the a/c on. Based on advice/theories floated on the board, I have replaced both the a/c relay behind the glovebox, and today I replaced the pressostat (low-pressure switch). Neither one made any difference.

I have come to the completely unsubstantiated conclusion that because a) I have the better paper/carbon filter on my rig, and because I live in a nice temperate climate (Santa Barbara, CA) where the outside air temperature is usually close to where I want my inside cabin temperature, I think my compressor is just working extra hard to keep the evap from freezing up. When the family and I travel to New Mexico this summmer, presumably in a hotter environment, I will be interested in seeing if the compressor still cycles as much as it is doing now.

That's exactly why it's cycling on and off like that, especially at this time of year.
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Chris Herbst, near Chicago, IL. 93 940, 91 240, 90 240, 88 740, 87 240

It sounds as if the charge in the system is low. It's hard to diagnose it without knowing the ambient temperature when you had the comp cycling on and off.

It wouldn't be unlikely that an 850 was low on refrigerant charge.
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Chris Herbst, near Chicago, IL. 93 940, 91 240, 90 240, 88 740, 87 240