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A/C compressor upgrade.

5

56pan

Active Member
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Location
North Carolina
I read on another forum about upgrading to a Sanden a/c compressor that has a higher output than the "pancake" style on my '93 C2500 6.5 diesel. Was told there was a good write-up about it on this forum but I can't find it? Can someone lead me to it? Thanks for any help.
 
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.

:banghead: 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.

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.

r134aR12.jpg

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
 
Last edited:
This is the link that I was talking about at DP:

AC compressor change

OK AC guys.... is this a good choice for a 93? http://www.classicindustries.com/product/truck/parts/346002.html "Except Diesel" The mounting on the AC compressor is different than gas engines including unique hoses. Simply put it won't fit with their gas engine (454, 350, 305, 262) adapter...
www.thetruckstop.us

Here is the bracket:
www.ebay.com

TBI CB-R4 - R-4 to Sanden Compressor Adapter Bracket | 1 Year Manufacturer Warranty

Use a 508 Sanden Compressor in place of an R4 Compressor with this simple adapter kit. R-4 to Sanden A/C Compressor. TBI Part Number:CB-R4. Conversion / Adapter Bracket Kit. NOTE: As pictured, this conversion bracket is designed for a serpentine belt application only.
www.ebay.com
 
WarWagon said:
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.

:banghead: 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.

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
Click to expand...

"Ask for the big R4: dual air 1995 11 CU compressor...." I'm assuming the big R4 will fit in the standard R4 mounts on my '93? I did the R134 conversion a couple years ago. New R134 condensor, replaced evaporator that had a pinhole leak and reman. R4 compressor and orifice tube. I've done quite a bit of auto a/c work and the system was absolutely evacuated and recharged correctly. Neither oil cooler is plugged with bugs/crud, radiator is also clear. Eng. has dual thermostat conversion and Duramax fan. The fan clutch seems to be working fine. If my truck sits in the sun here in NC for a couple hours and heat soaks, it takes too long to cool the cab down in my opinion. My son's truck is a 2000 K3500 standard cab (GMT400 body style) with the Sanden style compressor and under identical conditions, his cab cools down much quicker. I don't think there will be a problem with the length of the Sanden style compressor, as the truck has an intercooler and the intake tubing from the turbo's compressor straight the intake manifold is not there. If anyone has done the R4/Sanden compressor conversion with the adaptor brackets on a '92-'93, I'd appreciate hearing whatever problems they encountered. The dual thermostat conversion was supposedly bolt on and go, but I spent quite a while clearancing bracketry with a die grinder.
 
Welcome. I'm not any help on fitting the other parts unless I was there with a wrench in my hand. But I will re state one point warwagon touched on that will make a big difference on r12-r134a converted systems.

We know the difference of the to is 30% efficiency of heat drop. that coating for he mentioned averages 1/3 better btu expended.
Larger condenser and evaporator is the only fix there is, but often they simply wont fit.
Coating both the condenser and the evaporator fixes that issue perfectly. annoying to pull, but worth the results.

My preference, I would still change for the sanden compressor, they simply live longer.
 
"But I ain't_ever_replacing that evaporator again."

haha- you, me, and 95% of everybody else that has ever done one has that belief. Problem is I have worked on enough other rigs to know they get much, much worse. after a while at a shop doing about 25 of them in different rigs, I simply refused those jobs after a while. That is why my front heater core in my hummer remains shot and it was that way when I bought it in about 02. I hate them things.
 
smokymtn65 said:
I need him to come across the mountain and do mine! lol
Click to expand...
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.
 
Doing the evap in these isn't bad, the problem is the dash crumbles as soon as you touch it. As to the compressor, I've had great luck with GPD brand, it's the ONLY brand I will use. The r134 condenser swaps in, but you probably still have the smaller r12 evap as I don't think the r134 evap can fit in an r12 hvac box. There is also a scroll compressor out there that they stuck inside of an R4 housing, but it's said they don't work that well at idle. And I'm not that big of a fan of modern Sanden compressors after I lost shaft seals in a few at 2-3 years old. If you do go with a Sanden, I would stick with a SD7, not a sd5. Another thing many recvomend when converting GM's from r12 to r134 is to go with a Ford blue orifice(.067) instead of the stock .072 GM white orifice. Some even run the GM tan .062 orifice.
 
Good advice, sir, and I'll look for the SD7 compressor. Didn't know there was an R134 evaporator? Even if if would fit, I'm not replacing it. Have to disagree with you on that job. I've had my '93 for 21 yrs. now and have necessarily done a lot of work on it. Good old truck with a new paint job, but that evaporator replacement was far and away the worst work on it I had to do. Job from hell.
 
The 11 CU compressor fits 1993 fine. You do not want a smaller orifice tube if you go with the bigger compressor. I had a lot of luck with the VOV, Variable Orifice Tube, making a big improvement at idle. However YMMV the last VOV's I tried were all defective and stuck shut. (Charge AC system on high side and low side is still in a vacuum. Charge low side and it runs for a moment and shuts off as the low side is again getting no flow.)

I loved the working VOV in my 1993 and ran it till a R4 filled it with trash. Smaller Orifice tube diameters help at idle, but, the head pressure can get extreme at road speed due to sustained higher engine RPM and a bunch of other AC engineering and design factors. If you want some in depth from the fellow who invented the FOT system and a performance improvement on the dirt cheap FOT part check out an interview with him:

 
I had one of the variable orifice valves in my truck until the previous R4 compressor sh$t the bed. Blew trash all through the system, but I flushed it out real well and put on a new condensor. Easy to see why you can't flush a condensor anymore. They all seem to be parallel flow, not serpentine. That VOV did help the cooling at idle with mine also, but I had to get the truck back together and no auto parts store had the VOV in stock. Put the standard orifice tube back in. Do you have a link, War Wagon, for someplace with the 11 CU R4 compressor? I'd appreciate it. Good interview with Mr. Kozinski also. Thanks.
 
Twisted Steel Performance said:
Lots of ac service people don't know their is a different low pressure switch that needs to be used with 134 systems converting from r12 so the compressor cycles correctly.
Click to expand...
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.
 
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