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  #1  
Old November 28th, 2015, 19:44
simspace simspace is offline
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Jeep Cherokee A/C suction and discharge valves???

Hi All,

I bought a 1991 4WD Jeep Cherokee Laredo. I need evacuate the A/C. However the Jeep does not appear to have, what I consider, normal low-side / high-side Schrader valve connectors. As seen in the pictures below (as described in the '91-'93 FSM) you will see the suction and discharge valves on the back of the compressor. Each valve appears to be covered and has a valve stem which needs a knob of some sort to operate the valve stem.

My question is how does this work? How does one evaporate and charge this systems with R12? What kind of hose connections are used to evacuate and charge the system? The rentals at AutoZone use the manual Schrader valve connectors that clip on.

The vehicle is not drivable at this time, so I would appreciate avoiding comments such as "bring it to a service center" or voicing EPA concerns. I need to understand how these valve work.

Thanks so much,
Chris.










Last edited by simspace; November 28th, 2015 at 19:59.
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Old November 28th, 2015, 19:49
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Lkwelch Lkwelch is offline
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Jeep Cherokee A/C suction and discharge valves???

IIRC If you turn the valves all the way out you can charge/discharge the system. All the way in will allow you to remove the compressor without discharging the system.
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Old November 28th, 2015, 19:57
simspace simspace is offline
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Re: Jeep Cherokee A/C suction and discharge valves???

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Originally Posted by Lkwelch View Post
IIRC If you turn the valves all the way out you can charge/discharge the system. All the way in will allow you to remove the compressor without discharging the system.
Thanks for the quick response! Can you tell me what kind of hose connections are used to evacuate and charge the system? The rentals at AutoZone use the Schrader valve connectors. I don't think they will work in this case.

As far as opening and closing the valves, I suppose I can use pliers, but is there a specific tool used for these valves?

Thanks,
Chris
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Old November 28th, 2015, 20:00
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Lkwelch Lkwelch is offline
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Jeep Cherokee A/C suction and discharge valves???

I just used pliers, and the connectors you get now a days are for r134. You'll need to convert the system and buy some adapters. I think on my gauge set I could take off the connectors and the hose fit on one of the sides.
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Old November 28th, 2015, 20:06
simspace simspace is offline
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Re: Jeep Cherokee A/C suction and discharge valves???

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Originally Posted by Lkwelch View Post
I just used pliers, and the connectors you get now a days are for r134. You'll need to convert the system and buy some adapters. I think on my gauge set I could take off the connectors and the hose fit on one of the sides.
Awesome, thanks for the helpful comments! Hopefully the AutoZone kit can be used with adapters.

So I assume the R134 connectors are different than R12. I'll have to research that. Thanks again.
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Old November 28th, 2015, 20:09
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Lkwelch Lkwelch is offline
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Jeep Cherokee A/C suction and discharge valves???

They should, on my 89 I had to get a 90 angle on the high side because it's tight getting the connectors on.
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Old November 29th, 2015, 06:02
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Re: Jeep Cherokee A/C suction and discharge valves???

If you have the FSM there is a small section describing how to use those valves. The shaft with the square head can be turned in/out to isolate/expose different parts of the system. Namely you can close off the hose, which allows you to physically remove the compressor without losing your refrigerant (only lose what is in the compressor). You can also block off the Schrader valves so that refrigerant doesn't leak out.

The small caps cover up the R12 Schrader valves for adding/removing refrigerant to the system.

If the service valves work (are not frozen) then you can use a valve tool to remove the Schrader valve innards and install R134A adapters from NAPA/Ebay/wherever (good steel fittings, not junk ones).
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Old November 29th, 2015, 07:13
simspace simspace is offline
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Re: Jeep Cherokee A/C suction and discharge valves???

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Originally Posted by ehall View Post
If you have the FSM there is a small section describing how to use those valves ... If the service valves work (are not frozen) then you can use a valve tool to remove the Schrader valve innards and install R134A adapters from NAPA/Ebay/wherever (good steel fittings, not junk ones).
Excellent info, thank you! I thought R12 also used Schrader valves, but I wasn't sure if that was the case here.
The service ports looked odd to me. I suppose I never paid attention to pre '94 A/C systems.

Last edited by simspace; November 29th, 2015 at 07:17.
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Old November 29th, 2015, 15:22
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ehall ehall is offline
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Re: Jeep Cherokee A/C suction and discharge valves???

R12 uses Schrader cores but the external fitting is different
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