RANT... R134a krap gas conversion is assumed. R134a gives you less cooling with the inefficient R4 (ineffecient turns Horse Power, aka fuel, into heat that the condenser has to deal with) and higher head pressures when the heat of the summer really hits. As you may know this causes the R4 to expand the body and eventually leak at the O rings, run low on gas, loose oil flow from low gas conditions, and burn up filling the system with debris. Wasn't a good compressor even on R12. Ignorant stuff like this and running the Fixed Orface tube by the Big Three is one reason import cars with a TXV kicked their ass to bankruptcy out west. I live near Phoenix AZ and own my own AC recycle machine just for family and GM and Dodge AC problems in this heat. End RANT.
Welcome to TTS!
Before we start modding the AC system: what's wrong with it? I will suggest how you can get the best out of what you have and you can decide how extreme you want to go. Link at the bottom is one discussion of a Sanden bracket swap.
Ok, I ASSUME it's not working well. As you didn't give us much info you have to understand this is a big assume on my part. I hope it helps as this is the entire point: I have no idea what you do or don't know about this system so I will assume you don't and forgive me if you do.
Lets assume you wasted $50.00 on a charge it by the gauge can... Now you have no idea how much refrigerant is in the system. The only way to know is to evac the system and charge by weight. I say again best performance is by weight. 1993 is a weird year where most references do not have the correct R134a conversion charge weight. I have 36 OZ on the conversion sticker 2.25 LB.
If the R4 compressor makes noise it's done.
So how do you get the system to work well?
1) Replace the 6 blade fan with a 1998 9 blade steel or with trimming if needed a 2002 Duramax fan.
2) Low temp fan clutch like the Kennedy Diesel designed unit.
3) You have removed the engine oil cooler and cleaned the built up mat of debris off the condenser, right?
4) Move the transmission oil cooler behind the condenser...
5) Install an AUX fan kit like the 454's have to come on with the compressor.
6) Put a thermal dispersant coating on the condenser. @Twisted Steel Performance did one for my 2003 Dodge.
7) Ask for the big R4: dual air 1995 11 CU compressor. 11 Stamped on the compressor body, new only. Rebuilt is God doesn't even know what it is.
8) Shut off flow to the heater core. Keep unwanted heat out of the HVAC box.
9) Wiring problem on the R134a high side safety switch clutch diode. Check the location of the high side safety cut-out switch wire tie in to the AC clutch surge diode. The diode is 12" back in the harness from the compressor and some conversions make the safety switch arc till it welds shut due to opening the circuit and no clutch surge diode in place.
Link for #4
Relocate aftermarket trans cooler between condenser and radiator and add Aux fan...
In realizing that condensers should stay under 160 degrees I measured how oil coolers in front of the condenser heat up the condenser. The passenger side is the liquid feed to the evaporator so it's the most important. Here is how I mounted mine between the radiators. Downside is it's hard to...www.thetruckstop.us
Link for #6 :
https://www.thetruckstop.us/forum/threads/thermal-dispersant-on-an-ac-condenser-for-the-dodge.47232/
Let me expand on items 4 and 5. AC is simply moving heat from the cab via the evaporator to the outside of the truck at the condenser. If you don't have enough airflow of COOL air the condenser: it overheats and the AC quits working well. A quick glance at the R134a temp vs. pressure puts this temperature at 160 degrees. Tell me again why engineers and bean counters freezing their balls off in Michigan winters, and bluntly their cold summers all 2 weeks of it, keep putting 195 - 230 degree oil coolers in front of the condensers. The AC system will blow up anywhere over 400 PSIG. The relief valve is set to open around 450 PSIG. Usually the high side sealing washer on the compressor to hose just blows out on mine. The engine fan off due to a stone cold engine means no airflow unless you are doing 45 MPH - no airflow means the AC safety switch is opening after poor performance from a hot condenser. When the heat stops moving at a overheated condenser the AC quits cooling well.
View attachment 57635
IMO No room behind the compressor on the 1993 belt drive setup. Turbo intake in the way as I recall. Now if you got a later 6.5 belt drive setup (like 1996+) where the compressor is on the driver side...
Ask for the big R4: dual air 1995 11 CU compressor is also explained here as well as Sanden swap brackets:
Anybody Have Experience Replacing R4 Compressor with Sanden
It looks like the AC System in my 95 Suburban is on the way out. Anybody have any experience replacing the outdated R4 compressor with the Sanden Compressor? If so, what do I need? Bracket, lines, etc. TIA.www.thetruckstop.us
Wouldn't do it for all the money in Dollywood, bud. You're on your own on this one. I replaced the blower resistor, bad recirc. door actuator (that is impossible to replace without removing the dash), heater core and lubed all the linkages on all door actuators when I had the plenum on the workbench. Didn't want to go through that job again.
The r12 switch will still work, it will just cycle off around 40 degrees instead of 28-30 like most r134 switches do. R12 switches normally open around 28-30 psi instead of 18-22 like most r134 switches do. The good thing is many r12 switches are adjustable, so 1-2 turns and it's set for the lower r134 kick out pressure. If you're switching to HC based refrigerants, it's best to install a temp cutout probe directly into the evap.
