Hello and thanks in advance for any advice. 73 dart swinger 225 factory a/c. which is the high side and low side charging ports. I bought the 134a adapters but they each seem to fit on both ports? I believe I want to charge the system with the port on on the compressor?
high side and low side locations???
- Thread starter distel
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67Dart273
Well-Known Member
"Follow the system" tubes. You have a shop manual? WHY not Download one from MyMopar.
This is right out of the manual. The small tube coming out of the compressor is the "high" side. it goes to condenser, to receiver, and into firewall to evap
Large tube is SUCTION (low) side. It comes out of the evap (firewall) may go to an accumulator, and right into compressor
For reasons that makes no sense to me, this is REVERSED on the actual R-134 fittings. The LARGE R-134 fitting is HIGH side (red) and the SMALL R-134 fitting is SUCTION (blue) side
This is right out of the manual. The small tube coming out of the compressor is the "high" side. it goes to condenser, to receiver, and into firewall to evap
Large tube is SUCTION (low) side. It comes out of the evap (firewall) may go to an accumulator, and right into compressor
For reasons that makes no sense to me, this is REVERSED on the actual R-134 fittings. The LARGE R-134 fitting is HIGH side (red) and the SMALL R-134 fitting is SUCTION (blue) side
67Dart273
Well-Known Member
So far as charging, are you starting with an evacuated system? I would NOT charge initial charge into low side.
With a dead system in a vacuum, purge your charging can up to the manifold. Open the HIGH valve on the manifold, and with the can inverted, quickly open the can valve to charge as much LIQUID into the HIGH side. This will force a lot of refrigerant quickly through the system, through the evap, and back to the compressor. By the time it "gets back" to the suction side of the compressor, it will be vaporized.
Charge any needed remaining CAREFULLY with system running, with can UPright into the low side
Quite frankly, with the very basic question you've asked, you would do well to seek local professional help
Have you changed seals? Changed and recharged oil?
"WHAT I USE" for charging..........I just use store cans and a simple charging line "meant" to hook to the system port. Only I don't WANT to do that, I want to hook the can to my manifold. So I have an extra R-134 Adapter which I hook to the center manifold port, and then hook the "can rig" to that. I'll get a photo..........
I "used what I had." Because this manifold is R12/22/502, the gauge charts are only good for pressure. I have to use an R-134 pressure temp chart separately. The extra 134 fittings on the manifold are only to hang the hose quick couplers and keep them and the hoses clean
The center fitting has had a low side R134 fitting added, and "in operation" (charging) the can and hose you see there is snapped onto that fitting. In order to evacuate, I have to unscrew the center fitting and "go back to" an old school 1/4" flare service hose.
With a dead system in a vacuum, purge your charging can up to the manifold. Open the HIGH valve on the manifold, and with the can inverted, quickly open the can valve to charge as much LIQUID into the HIGH side. This will force a lot of refrigerant quickly through the system, through the evap, and back to the compressor. By the time it "gets back" to the suction side of the compressor, it will be vaporized.
Charge any needed remaining CAREFULLY with system running, with can UPright into the low side
Quite frankly, with the very basic question you've asked, you would do well to seek local professional help
Have you changed seals? Changed and recharged oil?
"WHAT I USE" for charging..........I just use store cans and a simple charging line "meant" to hook to the system port. Only I don't WANT to do that, I want to hook the can to my manifold. So I have an extra R-134 Adapter which I hook to the center manifold port, and then hook the "can rig" to that. I'll get a photo..........
I "used what I had." Because this manifold is R12/22/502, the gauge charts are only good for pressure. I have to use an R-134 pressure temp chart separately. The extra 134 fittings on the manifold are only to hang the hose quick couplers and keep them and the hoses clean
The center fitting has had a low side R134 fitting added, and "in operation" (charging) the can and hose you see there is snapped onto that fitting. In order to evacuate, I have to unscrew the center fitting and "go back to" an old school 1/4" flare service hose.
BillGrissom
Well-Known Member
I don't think there is an exact standard for R-12 fitting sizes. On my 1984 & 85 M-B cars, I recall both high and low pressure ports were the same fitting when I converted them to R-134A ports. Confused me for a while.
If you plan to convert from R-12 to R-134A at this late date, you might want to read up since R-134A is already outlawed in several countries and planned for the U.S. too. However, alternates also use the same R-134A fittings (Duracool, Envirosafe).
If you plan to convert from R-12 to R-134A at this late date, you might want to read up since R-134A is already outlawed in several countries and planned for the U.S. too. However, alternates also use the same R-134A fittings (Duracool, Envirosafe).
67Dart273
Well-Known Member
So far as I know, all "older" vehicles were 1/4" SAE flare schrader valve fittings, and "at some point" the high side became a smaller fitting. My 86/87 Ranger was 3/16 SAE flare on the high side, and kept 1/4" on the low. I had to buy a special adapter to fit the darn thing. It was R12 to the day I sold it.
Everything I worked on in HVAC/R was 1/4" flare. The R410 system I just put in for the neighbors is the same. I did have a Schrader core stick OPEN on the startup and it was a giant PITA. At the operating pressures of R410, this is a bit scary.
I had to pump down the system and change the core "hot." I was not happy. Having worked with hundreds of these in my "short career," I've had very few of them give trouble.
I still don't understand why 'n'ell they made the 134 low side the small fitting. This is completely opposite "the rest of the system"
Everything I worked on in HVAC/R was 1/4" flare. The R410 system I just put in for the neighbors is the same. I did have a Schrader core stick OPEN on the startup and it was a giant PITA. At the operating pressures of R410, this is a bit scary.
I had to pump down the system and change the core "hot." I was not happy. Having worked with hundreds of these in my "short career," I've had very few of them give trouble.
I still don't understand why 'n'ell they made the 134 low side the small fitting. This is completely opposite "the rest of the system"
67DARTGTCONV
Well-Known Member
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YOUR RIGHT, the Old R12 fittings were usually the same size. you would have to put adapters onto the original fittings to charge with R134 gauge sets
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