Should the engine be running warmer with AC?
 

Summer is here and there's been a lot of talk about AC so I thought I'd ask another one. I did a search but couldnt come up with an answer. I live in San Diego and got my R12 AC system working again thanks to a reputable shop down here. I have an 85 Carrera and really never used the AC much before. It blows super cold now but I notice the engine temps do run higher and somewhat erratic in the sense that sometimes and highway speeds the temp rises up to the 2nd white bar and sometimes when I'm idling it drops down to the 1st white bar. That doesnt make sense to me in an air cooled engine. Traditionally without AC on my car runs temp at the 1st notch. Please advise. Thanks!

Yes. The air that cools the engine first goes through the AC decklid condensor where it picks up heat so you are now trying to cool the engine with hotter air.

The variation is likely due to the compressor cycling on & off. One solution is to add a fan to the oil cooler in the passenger front fender well. It made a huge difference on mine. I never get above 9:00 on the gauge even when its 110 out & I'm sitting in traffic.

Thank you for the excellent answer. I really enjoy learning more about how these cars work from the pros on this board!

If you manage that in Tucson that auxiliary fan sounds like an excellent solution. Could you give me some info on the part? I spend a lot of time in Phoenix and I hesitate to take my 911 during the summer because of fears of overheating.

Yah the compressor drags a certain amount and makes the engine "work" harder as well as the warm air condensor thing.

Wayne's book has a section on the upgrade that will give you the general idea. On the 87 & later Carreras the fan was standard and if you can find the parts it should bolt right up on an 85. Buying one new is also big $$$$ but you may be able to find a used one. Another alternative is an aftermarket setup. I bought a kit from Elephant Racing that included the fan, relay and all the wiring. Still had to fab a bracket tho.