Montana2x2

Does anyone know if the HP relief valve is the same on I/C and Non I/C systems? I found the Non I/C # (4 seasons 35745) but cannot find a # for the I/C. Thanks.

thrashingcows

I found 4 seasons 35800 as the Non-IC unit. And I could not find a direct replacement listed for the dodge ram pick ups with IC motors...but the 4 seasons 35752 should work.

Montana2x2

I looked up the 4 Seasons 35752 and that is the low pressure cut out switch, that is the same I/C and Non I/C. The listing I cannot find for the I/C is the High Pressure Relief Valve mounted at the compressor. Thanks

maybe368

What I did was take mine into an automotive ac shop, showed it to them and he pulled one off the shelf behind him, they are apparently real common, something you might try...Mark

maybe368

35745 is the 4 seasons part number for the non-IC high pressure relief valve, see the last page here. If the valve looks similar to this it is probably the same...Mark

thrashingcows

I was not aware that there was a high pressure relief valve near the compressor. I looked at the NoN-IC one in the thread you linked there Mark...but what does an IC unit look like?

maybe368

I am not sure, I found a photo of of the ic sanden unit, SD7H15 and it doesn't show 1 mounted on the compressor. The non-ic unit mounts on the high side manifold. If someone with an ic truck could look at theirs and see if it has a valve mounted on the manifold. I can see mine from above. It is possible that they went to a switch with the intercooled rigs, but I am just speculating...Mark

maybe368

Is it on the compressor or on the manifold? If it is on the manifold, it is probably the same...Mark

thrashingcows

I have removed a couple IC Sanden A/C compressors, and have not come across any high pressure relief valve. Nor is there anything on the lines. My guess is that when they went to the Sanden compressors that this valve was not needed.

I put a Sanden A/C Compressor retrofit kit on my 68 Chrysler wagon...and there was nothing like a high pressure relief valve on that system either.

maybe368

That is likely, I cannot find any reference to one on an IC truck, anywhere. It may be internal...Mark

Jim Lane

On a Sanden compressor the high pressure relief will be on the head end between the head bolts and suction and discharge ports IF it has the option, there are many different head and fitting variants for the compressor.

The valve looks liks a short fat bolt with a hole in the middle, looks like the relief on a GM A-6 compressor.

The SD high pressure relief will vent between 495-525 PSI

I bought the high pressure relief for my C-171 compressor from my local AC repair shop, I think I paid around $20.00 for the valve and the gasket, If I recall correctly he said the valve vents between 475-525 PSI but this is by memory.

As you can see these are pretty serious pressures the system can attain, if they do not vent somehow lines will burst, your compressor will overheat and lock and burn off the belt or the compressor can explode.

High pressure happens when you loose cooling air through your condenser usually from a slipping fan clutch or a serious overcharge, damage can also happen if your blower motor fails.

The problem when they go bad, they will hold a vacuum when evacuated but leak under pressure and you can loose all of your refrigerant charge.

Worst case you could remove the valve and plug the port and then install a High Pressure Cutout Switch on the liquid line schrader valve to open the compressor circuit.

The brass plug on the side of the H-Valve that plugs the low pressure valve port fits the compressor perfectly.

Jim

maybe368

I cannot find anything about the Sanden hprv on the web. I believe the cutout that you talk about is what I saw somewhere on the web. That failure to hold pressure, while holding a vacuum, is exactly what happened to me...Mark

Montana2x2

The high pressure relief is where Jim said it is. I have not taken the compressor out yet but when I do I'll just pull the valve and try to match it up. If/when I find one I'll post the part number. I have not had any problem with it but R-12 is too expensive take a chance with an old valve. Thanks for all the info.

mhuppertz

Turned out to be this on the new receiver/dryer. Bought another and it seems to be holding.

maybe368

That looks like a high pressure relief valve...Just kind of short...Mark