R12 - Recharging Question ?

[OwnerCS]

Much to my surprise, my Q has been running with R12 all this time. The compressor was working a couple of months ago -- now suddenly it stopped engaging.. I'm sure the freon level has dropped below the point where it will allow the compressor to engage.. I'm surprised it lasted this long..

So I talked to my buddy the Infiiniti tech out repair options. There is some conversion kit and system flush that he can run change the compressor oil to prep the system for R134a for roughly $300. He indicated he will fix any seal leaks that show up immediately after the job. However he indicated it could become a stream of leaking components afterward as the R134a runs at a higher pressure than R12.

Has anyone had experience with a G50 system converted from R12 to R134a?

[Q451990]

Dennis used to say that since the components for 134a were all different, the only "correct" way to make the change was to change out the condenser, evaporator, etc.

I think I'd try to get it recharged with R-12, even though it will be more expensive for the refrigerant. Long term I suspect you'll have fewer issues crop up. There are some R12 alternatives available with names like "freeze 12" that might work too.

Heath

[Infinitiguy19]

Get a 609 EPA licence and buy R12 yourself.

[OwnerCS]

Get a 609 EPA licence and buy R12 yourself.

Thanks Paul. I just got 609 certified and bought 2 cans of R12 for $20 each..

[OwnerCS]

Now that I have some R12 and R12 gauges for refilling on the way -- how do I get the compressor to restart after I hook up the hoses and release the refrigerant? Will the system detect the pressure increase and engage the compressor clutch or does a fuse need to be replaced or bridged to make contact?

[qship96]

put just enough r12 into system to trigger compressor,then have system professionally sniffed to find the leak,then evacuated down to save the freon in system and repair any/all leaks,then vacuum to remove moisture and finally recharged with r12.Good idea to install a new drier during the procedure.

To just refill with your new r12 without doing all the above would be a total waste of $$$ {r12} as you already know you have leaks in the system!

Here is a link to a great forum for automotive A/C information.http://www.autoacforum.com/categories.c ... &zb=642761

[OwnerCS]

Thanks Qship!

[OwnerCS]

I purchased some R12 and an R12 gauge set. I tried to hook up the gauges without success. The blue to (low side) connected ok. However, the red (high side) doesn't fit. The Red fitting is smaller than the other fittings. Does Nissan use a smaller fitting for high side R12 connections?

Next I tried a straight fill using the yellow line into the low side. The system would not take freon. Could the compressor not starting may be an electrical issue?

For the high side valve, I found I needed a schrader valve..

I picked up one below.
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0735584135


Any ideas?

[Q451990]

I haven't recharged the Q, but I do recall having to jump out the compressor clutch relay to get it to accept refrigerant when I recharged my '97 truck. The systems are very similar, so I'd expect the same thing on the Q. Essentially, the compressor is locked out while the pressure is too low - so you're bypassing that in the dual pressure switch by jumping out the contacts in the relay harness.

How difficult/expensive was the 609 certification?

Heath

[OwnerCS]

Heath - That may be it.. I was able to dump freon into the Maxima and it picked it up and started the compressor. So I incorrectly figured the Q might work the same way..

Any tips on the how to jumper the contacts in the relay harness?

The EPA test was $19.95 at the following location. I took the test one morning at 4:00 AM after studying for a couple of hours. The practice tests will get you ready.

http://www.epatest.com/609/openbook/

[Q451990]

I think the issue may be how low the system is. If you're just below the drop out point on the low side of the sensor, then the can will probably push the pressure into the working range. If it's way down, then the pressure from the can won't push it up to the working range.

I'll have to look in to that certification... for $20 my stash would be "legal"

Heath

[OwnerCS]

Heath - It looks like Page 88 of the manual provides information on the pressure switch. Can you provide any information on how to jumper the switch to start the compressor?

[Q451990]

I just jumpered the "business" side of the A/C relay with a pair of needle nose plyers. It's the last step between the ECU and the clutch.

Heath

[OwnerCS]

Did you completely pull the A/C relay in the box by the battery and jumper the pin connections in the board?

[Q451990]

Yes. There will be two pins for the control voltage to the relay, and the two that the relay shorts out when switching the compressor clutch on. You should be able to tell which ones to jump by the diagram on the top of the relay.

Heath

[OwnerCS]

Thanks Heath - It was the two rightmost plugs under the A/C relay that I jumpered. I added one can of R12. The car was cooling normally again after one can. I'll post some pictures in a couple of days for others to see the operation.

[Q451990]

Nice!

[OwnerCS]

After recharging this year, my low side reading appears to be too high (30) with the high side (100) reading at an ambient temperature of 75F. In looking at some charts my low side should be 16 with a high side of 160 to 190 for an ambient temp of 75?

The compressor runs but no cooling.

Any ideas when the low is too high and the high is too low? The FSM indicates a worn compressor.

[DrewQ45]

Probably a moot point with this thread, but I converted an 90' G50 to R134 and it worked just fine.

ac-converting-90q-to-r-134-t235199.html?hilit=AC conversion