capecorvette

ok, bought the kit from autozone. i put on the new valves and started to charge system. the pressure was way too high so i stopped. the system was taking in the freon, but the return line was as cold as the other line. my neighbor who is a mechanic said i have a blockage on the high side line. he suggested its the dryer. the ac in this car has not been used in years and there was no r12 in it. he thinks the dryer is blocked and full of junk so that is causing the high pressure.
so would you guys agree its the dryer or do you think it could be something else? I am selling the car and I don't want to replace every piece of this system, here in new england we only use the ac for a few months anyway.

thanks

71 Green 454

What year is your car? You really should have replaced the drier/receiver anyway. I'm curious to find out how your conversion turns out.

capecorvette

It is a 79

thegazman

Did you replace the oil in the compressor with a 134a compatible oil and the orfice tube that causes expansion of the refrigerant as it enters the evaporator.

Artsvette73

This will cost ya to get it right. Sell it as is.
Find your leak first or you are wasting time and money
Dryer should be changed
Change all o rings
System flush
New orfice tube
Add 134 oil
Evacuate the system
Hope for the best

markdtn

Replace the dryer and orfice tube. NEVER try to re-do an a/c system without replacing these. You are asking for problems, which you found. Sounds like the dryer was saturated with moisture from the empty/unsealed system. Working a/c will generally be worth the repair cost at resale.

G dad

[QUOTE=markdtn;1566931526]Replace the dryer and orfice tube. NEVER try to re-do an a/c system without replacing these.


I did this with my 79 recharged it...works fine. Make sure you evacuate the system.

7T1vette

If you didn't vacuum the system down, you probably have moisture in the line and it just froze up. Let it sit to stabilize temp.; then vacuum the system.

TimAT

Flush the system! Replace the dryer and install a blue (ford) orifice. Add the correct amount of 134 compatible oil, after pulling a vacuum and charge it with 10% less 134 than you would with R-12.

capecorvette

how do you pull a vacuum on these systems?

MikeMc71

With a vacuum pump.

71 Green 454

A/C Tools:
http://www.corvetteforum.net/c3/zwed...e/ac/tools.htm

Bobz08C6

Tim,
Doesn't today's R134a refrigerant cans come with the correct amount of oil in the can along with the refrigerant? Other than putting a little oil in the compressor to lube it if you are replacing the compressor do you really need to add oil separately?

7T1vette

I know that R-12 came with the lubricant already in the can...I don't know about R-134, but I would guess that it did. [nothing on the can about it?]

It doesn't sound like you vacuumed the system down. With luck, you only froze up the coils until you turned it off. Not sucking the system down has caused compressors to lock up...permanently.

Mia

Wish I would have found this thread first before starting a similar one. A lot of good info here. Looks like this is one NON-DYI job for me this time around.

CA-Legal-Vette

I found the vacuum pump to be good for leak detection as well. Once you've evacuated the sytem for long enough to remove the moisture, you shut off the valve and let it sit with the pump off. If the level of vacuum changes, you have a leak. Listening for the hiss should help locate all but the smallest.

71white

Harbor Freight tools is selling a vacuum pump for less than $20, does it work??

Bobz08C6

I bought this on EBay a few minutes ago. It looks like it will do the job. I plan on replacing my compressor, orifice valve, dryer, accumulator and any other component I can get my hands on and flushing out the system. I'll do this in the spring.

I've never done anything like this before but I have some confidence now after reading a lot of very useful info from all these helpful CF bros.

http://cgi.ebay.com/ebaymotors/New-A...=p4506.c0.m245

MikeMc71

The gauge set looks ok, not sure about the pump, though. I have never used on that small before.

R134 may come with lubricant, its ok to top off, but to replace componants and recharge, I wouldn't do it myself.

If you are just doing the dryer and expansion valve, its probably ok.

If you are converting from R12 to R134a you need to change all the oil in the system, otherwise you are asking for trouble. The older R12 oil will not be compatable with the 134a. You also have to be careful, because some of the older componants in the system may not be compatable either.

You also must have gauges to get the 134a charge right, because the site glass alone will not be a good indicator for the 134a.

70ZZ3 96LT4

capecorvette I do not know the specifics of your 1979's A/C system, however my 70 A/C has an expansion valve and the line connecting to the expansion valve coming from the condenser has a small metal screen/filter in the expansion valve connection. If a dryers desiccant bag/container has leaked desiccant it will travel to the expansion valve and stop the flow of R12 or R134. It happened to my 70 in 1988. GM dealership mechanics could not find the problem, I did by reading my service manual.