A/C cycle help

[vkohanski]

I didn't see a different place for this, but...

Just got this '87 GN... the A/C is cold, but seems to cycle off when you take your foot off the gas. When you get going, it's nice. Stoplights... things get warm. Any suggestions? It seems to do it in both max and norm settings. I've never seen something like this before. Not sure if it's a relay, or whatever.

 

[TurboBuRick]

When they are low on freon the will cycle.

 

[vkohanski]

OK cool. I hadn't had one blow cold when it was low, but I'll try that first. Thanks.

 

[86Nick]

Sounds like low on freon. When you throttle the car up or driving the compressor spins faster circulating the freon faster in the system. Also while cruising you are passing more air threw the condenser which is help the heat exchange process of the freon. You could also have a bad low pressure switch.
Install a set of gauge and check the pressures. with 134 low side 30-40 high side 150-175 r-12 50-60 on low high 250-275

 

[vkohanski]

Good suggestions, but I wasn't quite so lucky. Compressor is fully charged. Clutch surfaces are bad and it's struggling to engage - sparks everywhere. When it engages, it's cooling nicely, but it's cycle-to-cycle on whether it engages, or not. By the time I finish messing with a clutch, it's usually easier to just replace the whole thing with a brand new system. Systems get a real good workout down here in Houston. Thanks for helping on the suggestions.