A/C Questions!

[wertygrog]

Hi,

I'm a new owner of an '84 944NA, and one of the remaining issues with it is that the A/C system doesn't work. I am a beginner when it comes to a/c as my daily driver has always been a 914 (I'm still in college). Don't get me started about the fuel injection craziness!

The first issue is that the evaporator fan only runs on high. I traced the issue to the fan resistor pack using the electrical diagrams, but I can't seem to find where the resistor pack is in my early 944. I suspect it's on top of the evaporator box under the passenger side dash.

How do you remove that box? I found a few bolts but I couldn't seem to drop the unit down. Is there a guide for this somewhere?

Also I've determined that there is 0psig in my A/C system. It has the original schrader valves so I'm assuming it was never filled with r134 and its associated oil. Before I take it to get filled, and since I don't have a vacuum setup, could I use my air compressor to fill it up to maybe 30psig to check for leaks? Maybe spray some soapy water on the hoses?

Also, is it imperative to get the system evacuated before filling, or can I just add a bunch of r12 substitute and oil? I mean does the refigerant displace the air, or is there a bleeding procedure? I'd rather not convert to r134 because I'm afraid of the higher pressure blowing hoses off- I'd rather spend a little more for the duracool then shell out a couple hundred (at least) if something else goes wrong.

Finally, I'm not getting 12V at the low pressure cutoff valve. This is with the ignition on but the car off (and the A/C knob turned). I know the wire leads to an amplifier of some kind. Where is this amplifier on my early year car, and is there any way to test it?


Thanks a ton in advance for your help!!!

[John_AZ]

Living the college life in Daytona Beach! Never got there on spring break.

Really many issues and I only have one answer. Yup, you need to evacuate. You could go with one of the cheap Harbor Freight vacuume boxes but they really do not work well.

Here are a couple of links to review before a pro offers advice.
http://www.griffiths.com/achelp/achelp2.html
http://www.the944.com/ (Press infor for A/C 134a)
finally:http://www.aircondition.com/

GL
John_AZ
1988 924S + 1987 924S DD

[Zero10]

Forget duracool, use red tek. At least sniffers can pick the stuff up.
If your system is empty then you have a leak, and when leak hunting sometimes a sniffer is your best friend. With red tek it is not that important to evacuate the air, rather, they recommend not doing it, but you should change your receiver/dryer to prevent any moisture problems. Pressures are comparable to R12 however the cooling is much better. This is the best alternative IMHO.

I don't know much about the early A/C systems, but if you have no power to the low pressure switch with the A/C switch on then my guess is that the A/C switch is no good. Far from an expert here though

[wertygrog]

Hi John, how did you know I chill in Daytona? You didn't miss much for Spring Break, my buddies and I typically head out of town that week.

I'm a little confused by the944.com...are those weights just for the oil, or the oil and refrigerant?

Zero, where can I get a sniffer? Bring it to a shop? As for the leak, I'm hoping that I can pressurize the system with air to find any leaks...I'd like someone to confirm that that's a good idea before I try though. All the lines and everything look good, so I'm hoping it's a small leak and that the system hadn't been refilled in a long time.

the red tek looks good, where can it be bought? They have a dry32 product that is supposedly a gaseous dessicant of some kind...

thanks for the responses! Does anyone know how to remove or dissasemble the under dash ac unit?

[mattdavis11]

A/C amplifier is under the passengers side kick panel, below and to the right of the glove box, as is the relay. It's a black box about 3x5x1. I had a burnt trace on my amplifier which lead to a problem similar to what you are having. I soldered in a jumper and it works fine. I know when the front seal went on my compressor it shorted to ground and took out the amplifier.

I don't recall where the bridge resistor is for the evaporator fan, but I can look.

You will most likely need more than 35psi to find leaks, but you have the right idea. Nitrogen would be best, but I've used compressed air tons of times. You need to get the moisture out of the system, so yeah vacuum it down. You can fill without pulling a vacuum, but I wouldn't recommend it.

As for refrigerant, 2.09 lbs of R12, 90% of that for freeze 12, and 80% for 134a. I forget on the oil charge, but 5-6 ounces ought to do. Use Pag 46, never had a problem with it in any of my cars.

[wertygrog]

Hi Matt,

I found the amplifier tonight, the PO had stuck it above the evap fan motor. There were two burnt traces, so I soldered some jumper wires. Can you explain how the front seal took out the amplifier? I'll have to check that if I had the same amplifier issue.

If you could look up where the resistor is, that would be great because I can't find it anywhere!

I'll try adding air to find the leaks, what psi do you recommend? And where is the best place to get a receiver-dryer?

Thanks for your help everyone!

[mattdavis11]

When the front seal went the compressor electromagnetic clutch must have shorted to ground. They both went at the same time so that's the only way I can explain it.

I did not see the location in the factory manual, sorry.