dstt

On my '84, I have noticed that the a/c cuts out when the engine is under load. It will not do it when just revving the engine out of gear, but when accelerating or pulling up a hill, there is a definite change in the sound of the blower fan and the air output from the vents cuts to nothing. Anyone know if this is normal? I don't remember this happening on my '86.

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'84 guards red commuter
'86 graphite project

Stan944

I think that's how it should be, but wait for more answers.

Porsche-O-Phile

When under load or when at low RPM? There's a difference. The systems in these cars (or pretty much any car) will have lesser performance at low RPM than when the compressor is spinning away.

dstt

No, under load. For instance, running 65-70 on the freeway, and then having to accelerate to pass or give it more gas to maintain speed up a hill or incline. Basically, when the mpg needle(which I assume is just a vacuum gauge) dips, the fan blower changes tune and the output of air at the vents largely disappears.

onewhippedpuppy

Hey, I have that same problem on my 951! Only seems to happen with the A/C, not with vent or heat. I had wondered about some sort of a ground issue, never got around to asking anybody though.

onewhippedpuppy

Any suggestions?

hosrom_951

I was told by several rennlisters that at WOT (open throttle) the a/c should cut out, thus giving the "power" back to the engine.

That is not the case with me, nor ever was in either my current 951 nor my 88 NA (RIP).

83na944

My 83 did not do that.

Since the ducts are controlled by cable on the early cars, it is not a vacuum issue.

Some cars have a cutout switch that cycles off the compressor, but that wouldn't change the airflow and I don't think the 84 had a cutout switch.

I suspect there is something electrical going on there.

onewhippedpuppy

Sounds like a good excuse for some Ice Shark ground cables!

Chris_924s

Any tips, tricks? best or worst methods and kits?

Just wondering if it's a viable option to wholesale replacement/swap.

TIA.

onewhippedpuppy

I've seen good things about Freeze 12 on here, cheaper than a conversion. May be BS, but I've heard that when an original R12 car is converted to 134a, it never works as well. Something about the initial design not being optimized for the 134a.

Mouthpiece

I had a similar problem until I had the A/C recharged. I paid the $50 for the R-12 and let my mechanic do it.

onewhippedpuppy

Terry, your A/C cut out at higher RPMs because it was low on freon? I've never heard of that, but our cars are a little different.

alpenweissisnice

Speaking of freeze 12, I bought a 3 can kit with the adapters and charge hose that I no longer need. I found another source for R12 (don't ask) and I'm going to forgoe the process. If you are interested, I'll take 25 bucks plus shipping. Attached is an eBay link for what I bought...Lemme know...

http://cgi.ebay.com/ebaymotors/ws/eB...category=46094

83na944

Hey Chris_924,

I converted my 83 944 to R134a a couple of weeks before it was totaled las Summer. The conversion went smoothly. I bought gauges and a conversion kit, a couple of sets of "o" rings, some system flush compound, and a new drier. I rented a vacuum pump for a tool rental store. I also had the R12 removed for $20.

After it was evacuated, I disconnected the compressor, drained the old oil, and added the same amount of new PAG oil plus a couple of ounces and installed the new fittings. You'll want to invest in a set of 90 degree fittings becuase the space is tight.

I flushed the condensor, then installed new "o" rings everywhere I could get to. Then I installed the new drier and tightened all connections. I hooked the vacuum pump and pulled a vacuum on the system for an hour to remove all of the moisture in the system. I let it sit for another hour with the vacuum to assure there were no leaks.

Finally, I charged one can of R134a to get the system going, then started the car. I let the compressor pull in another can and a half. Actually, I kept up with the weight of the R134a I used. You need about 80% by weight of the amount origianlly charged with R12.

The system worked great - 35 to 40 degree temperature drop out of the vents. Key issues are remove the R12, replace the drier, replace the "o" rings, replace the oil, pull a long and lsow vacuum on the system, and charge by weight.