AC line Switches

[Subfixer]

I'm swapping out the entire AC system from my 92 R12 to the 94-95 R134a system.


I've got everything I need except 2 pressure switches, which I can't seem to identify correctly via the many vendors out there.


The AC system has 3 pressure switches. One on the Evaporator itself, and 2 on the line that runs from the Evap to the Condenser.


I need the GM or AC Delco part numbers for the 2 on the Evap to Condenser line for 94-95 ZR1.
These 2 switches are different from 90-93 (R12) vs 94-95 (R134a).
The thread sizes changed.


Thanks, Paul

[secondchance]

Originally Posted by Subfixer

I'm swapping out the entire AC system from my 92 R12 to the 94-95 R134a system.


I've got everything I need except 2 pressure switches, which I can't seem to identify correctly via the many vendors out there.


The AC system has 3 pressure switches. One on the Evaporator itself, and 2 on the line that runs from the Evap to the Condenser.


I need the GM or AC Delco part numbers for the 2 on the Evap to Condenser line for 94-95 ZR1.
These 2 switches are different from 90-93 (R12) vs 94-95 (R134a).
The thread sizes changed.


Thanks, Paul

Below are part numbers you are looking for:
AC Delco #15-2878 Switch AC Compressor Eng Cool Temp (Fan Switch)
AC Delco #15-2877 Switch AC Cycling (High Pressure Switch)

AC Delco #15-2878 also has GM part number 10223909.

https://www.ebay.com/itm/1994-95-c4-...kAAOSwImRYkI1-

I know it's not cheap but very tough to find. Somehow, there is one on ebay - not my listing

[secondchance]

Seems AC Delco 15-2877 is also for sale.
https://www.ebay.com/itm/ORIGINAL-AC...0AAOSwImRYikhC

[Subfixer]

Thanks. I was able to get both.

The 15-2877 (10223908) was available for only $12.95 from https://www.gmpartsgiant.com/parts/c...~10223908.html

Bit the expensive bullet for the other switch.

[lfalzarano]

Originally Posted by secondchance

Below are part numbers you are looking for:

AC Delco #15-2878 Switch AC Compressor Eng Cool Temp (Fan Switch)

AC Delco #15-2877 Switch AC Cycling (High Pressure Switch)



AC Delco #15-2878 also has GM part number 10223909.



https://www.ebay.com/itm/1994-95-c4-...kAAOSwImRYkI1-



I know it's not cheap but very tough to find. Somehow, there is one on ebay - not my listing

Do you need to change out the compressor or just the switches to use the R134a?


Sent from my iPhone using ZR-1 Net Registry

[Subfixer]

Originally Posted by lfalzarano

Do you need to change out the compressor or just the switches to use the R134a?

For my particular project, I have changed the entire system; Compressor, all hoses, condenser, dryer/accumulator.


The only original part is the evaporator.


The project began with a compressor/ condenser change. The 94-95 condenser is a different design better suited for R134a refrigerant. The original compressor was shot, so I bought one that was already set for R134a. Has the correct PAG oil already in it.


The new condenser and dryer have slightly larger fittings, so the original hoses will not fit. Once I received the correct 94-95 hours, it turned out that the 2 switches in the high pressure line had a different thread pitch from the '92 R12 switches.


As posted in other AC retrofits, R134a will work in existing R12 systems as long as the R134a adaptor fittings are used and the mineral oil in the system is completely flushed out.


I changed it all because I felt GM knew what they were doing (better than me) when they redesigned the AC system for R143a.

[lfalzarano]

Hoping that it is just a faulty switch. Mine was upgraded to R134a many years ago by GM. Worse case is the compressor has to be replaced. I spec’d one out from Jerry’s.

Thanks for the advice on what you did, and BTW - you are probably smarter than the GM engineers.


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[Subfixer]

I've been working on this system today, and it turns out I need an evaporator also.
There are 2 different part numbers. R134a 94-95 is 52463787, R12 90-92 is 52456459.

When GM switched to R134a, all the fittings changed either thread pitch and/or connection diameter. The connection diameters changed by about 2mm, just enough where R12 and R134a system components will not fit together.... ugh...

[lfalzarano]

Now there must be some stupid reason for changing the threat pitch and diameters by GM! [emoji16]


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[Subfixer]

Got the evaporator out using the "split case" procedure I found on this forum. Not very hard, just a lot of bolts and interference to get out of the way.
Removed coolant tank, washer fluid tank, diagonal brace bar, heater hoses.
After getting all the 7mm bolts out of the case, including 2 from under the car, the 10mm bolts from the firewall, the side of the evaporator case came right off.
Now just waiting for more parts to show up.....