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Re: 1961 cadillac conversion

Posted: Wed Jul 08, 2020 12:40 am
by Al9
Just make sure to have a binary/trinary pressure switch somewhere on the high side that turns the clutch off once the pressure gets too low. That way the compressor will be spared in case the system suddenly loses a large amount of refrigerant for whatever reason.

Prolonged operation with low refrigerant levels, even if the compressor doesn't seize up, might create considerable amounts of wear (i.e. increased piston blow-by, eventually getting to the point that the variable displacement mechanism is no longer able to regulate piston stroke correctly resulting in a weaker and noisier compressor).

Re: 1961 cadillac conversion

Posted: Mon Jul 13, 2020 10:01 pm
by bohica2xo
Is that the Holley 20-131 compressor bracket you are using?

Re: 1961 cadillac conversion

Posted: Tue Jul 14, 2020 3:03 pm
by cadillac matt
i'm using the 20-132 bracket set for the sanden comp. i can get just the comp. bracket for the r4 if needed. i'm leary of using a r4 comp. they have a bad rep.

Re: 1961 cadillac conversion

Posted: Tue Jul 14, 2020 4:40 pm
by bohica2xo
The R4 would go 80,000+ miles around here in a Suburban with dual A/C running limo duty.

What seemed to kill them was either running them with a low charge, or exterior corrosion.

Cheap remans from sketchy sellers made them sound worse than they really were. Add to that the learning curve - in 1995 we were just starting to see serpentine and parallel flow condensers. People were still trying to flush those condensers after a compressor failure. Not realizing the condenser was the primary filter.

Around the same time we heard a lot of talk about Ford compressors & "black death". Axial piston FS10 style compressors failing for "no reason" leaving black goo in the system. Lubrication failures with polymer piston rings and SEC PAG. Lots of learning went on in the early 90's with 134a, condenser & lube changes.

Todays lubricants, better manufacturing tolerances than ever before - and a better understanding of the refrigerant system requirements would make a new R4 an acceptable compressor. It has enough volume for your needs, it is a direct bolt on & is compatible with your existing CCOT system. Your only problem with your system right now is a lack of pumping capacity. An R4 is the most direct bolt on solution.

Use the standard piston R4 with the small diameter serpentine clutch (Ex. 1995 Suburban application) and avoid the "scroll replacement" - china slapped a small scroll in an R4 can and they have a really poor reputation around here.

Re: 1961 cadillac conversion

Posted: Wed Jul 15, 2020 2:22 am
by Al9
That PAG 150 is surely going to get really thick inside a cold evaporator. Maybe that's what aggravates oil return issues with low charge.

Re: 1961 cadillac conversion

Posted: Wed Jul 15, 2020 8:30 am
by bohica2xo
Again, the R4 does not do well running on a low charge - but neither does ANY other compressor.

The SEC PAG oils of the 1990's were garbage. We ran BVA POE 100 in all of the R4 compressors without any issues. Idling for hours in the 110f heat.

.

Re: 1961 cadillac conversion

Posted: Wed Jul 15, 2020 9:09 am
by cadillac matt
wow. more good info. thanks again! what would be a good brand for a new r4?

Re: 1961 cadillac conversion

Posted: Wed Jul 15, 2020 2:24 pm
by bohica2xo
I have not bought a new R4 for a few years. Contact Tim, he will know which supplier has their act together. I buy compressors from him.

Use whatever oil the compressor manufacturer recommends. If it is PAG, make sure it is the DEC variety.

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Re: 1961 cadillac conversion

Posted: Wed Jul 15, 2020 4:12 pm
by cadillac matt
thanks again.

Re: 1961 cadillac conversion

Posted: Wed Jul 15, 2020 4:30 pm
by Tim
Original GM R4. Still not the quietest compressor out there. So take notice before ordering.

https://ackits.net/product/14-20189/