My compressor is getting noisy and I want to change it. Its the original pancake style. Someone suggested I go to a Sanden. Whats entailed in this? What parts do I need? Is there a kit for this? Need a little guidance, also someone said the condenser on the 93 is too small, is this so?
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AC compressor change
- Thread starter Hill Top
- Start date
Never found a Sanden "kit" as the diesel install/clearance is different than gas engines.
Replace compressor with one from a dual air suburban (1995) for highest CFM, flush system, replace accumulator, Replace orface tube suggest VOV 105 degree option, add oil. Note the sealing washers on the back of the compressor are a PIA to get correct as you are going from a R12 lineset to a R134A compressor. They do not make the R12 offset anymore where the lines seal to the compressor so you have to use different thickness sealing washers. Check the hoses and have the lineset rebuilt if there is any question as to their 25 year old condition. Main cause of compressor failure is it running low on R12/R134a.
Was your system converted to R134a? Make sure there is a high side cut out switch on the compressor if it was converted.
You have an old tube and fin vs. a R134a parallel flow condenser. The parallel flow is more efficient for R134a and worth changing out if you use the krap R134a. @Burning oil is the only one I know of to experiment with a larger condenser. R12 or alternative refrigerant (propane with butane) are better choices. R12 is around...
The VOV is a self adjusting orface tube that gets you a little more performance out of the system it will be a $20.00 vs a $2.00 part. http://www.imcool.com/articles/aircondition/VOV2.php
Rock Auto catalog:
http://www.rockauto.com/en/moreinfo.php?pk=869808&cc=1052514&jsn=465
http://www.rockauto.com/en/catalog/...heat+&+air+conditioning,a/c+orifice+tube,6936
Replace compressor with one from a dual air suburban (1995) for highest CFM, flush system, replace accumulator, Replace orface tube suggest VOV 105 degree option, add oil. Note the sealing washers on the back of the compressor are a PIA to get correct as you are going from a R12 lineset to a R134A compressor. They do not make the R12 offset anymore where the lines seal to the compressor so you have to use different thickness sealing washers. Check the hoses and have the lineset rebuilt if there is any question as to their 25 year old condition. Main cause of compressor failure is it running low on R12/R134a.
Was your system converted to R134a? Make sure there is a high side cut out switch on the compressor if it was converted.
You have an old tube and fin vs. a R134a parallel flow condenser. The parallel flow is more efficient for R134a and worth changing out if you use the krap R134a. @Burning oil is the only one I know of to experiment with a larger condenser. R12 or alternative refrigerant (propane with butane) are better choices. R12 is around...
The VOV is a self adjusting orface tube that gets you a little more performance out of the system it will be a $20.00 vs a $2.00 part. http://www.imcool.com/articles/aircondition/VOV2.php
Rock Auto catalog:
http://www.rockauto.com/en/moreinfo.php?pk=869808&cc=1052514&jsn=465
http://www.rockauto.com/en/catalog/...heat+&+air+conditioning,a/c+orifice+tube,6936
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Will L.
Well-Known Member
If you have real r12, it does work better. But you might be able to sell it for enough to pay for an entire new system...
Head pressure is way higher for R134a on a 1970's R4 compressor design that wasn't a great for the lower head pressure of R12. R12 is colder when it matters the most on an extreme heat day. (R134a simply quits on most systems over 105 degrees due to extreme head pressures without high CFM airflow over the condenser.) I would make sure there are no leaks on the system before gassing it up. Recall the R12 uses mineral oil vs. the R134a PAG oil.
Real R12 is an investment or are you going to enjoy it?There are no upgrades required for R12. I would put a high pressure cut off switch kit in the new compressor like R134a retrofits require as it is possible to get high pressure with R12.
If you convert to R134a you need a new parallel flow condenser (Parts stores appear to have this as an option for 1993 or order a 1994 R134a condenser) to get the most out of it esp. in Texas heat. Flush what little of the system you are not replacing, PAG 150 oil 8 oz, condenser, accumulator, new hoses, and you are replacing the compressor anyway.
You could look at alternate refrigerants (propane mixes) however they tend to ice up the evaporator as some blends are not easily controlled by pressure. Envirosafe Industrial is the specific example of icing the evaporator solid on med/low fan speed as the GM pressure switch is not calibrated for this blend.
Real R12 is an investment or are you going to enjoy it?There are no upgrades required for R12. I would put a high pressure cut off switch kit in the new compressor like R134a retrofits require as it is possible to get high pressure with R12.
If you convert to R134a you need a new parallel flow condenser (Parts stores appear to have this as an option for 1993 or order a 1994 R134a condenser) to get the most out of it esp. in Texas heat. Flush what little of the system you are not replacing, PAG 150 oil 8 oz, condenser, accumulator, new hoses, and you are replacing the compressor anyway.
You could look at alternate refrigerants (propane mixes) however they tend to ice up the evaporator as some blends are not easily controlled by pressure. Envirosafe Industrial is the specific example of icing the evaporator solid on med/low fan speed as the GM pressure switch is not calibrated for this blend.
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I would leak check the system and for good measure rebuild the hose set. (~$100) Mine leaked at the high side hose crimps by the radiator. Likely your compressor body or shaft seal was the source of the leak.
Have you cleaned the stack and checked the KD fan clutch over for leaks working properly? AC systems die quick from lack of condenser cooling.
Note the 1995 and lower years "Dual air" has a higher CFM compressor for better idle cold air. This is the only upgrade you may consider, but, R12 may work fine on a standard CFM compressor. I locate (GM, Junkyard, make my own) and use the insulation around the accumulator. I also insulate the line from the condenser to the evaporator.
The R4's no longer have a "lifetime" warranty. Yeah, they don't last. They are VERY sensitive (over other designs) to low charge as this interrupts oil flow to them. The R4's help kill themselves as they leak everywhere mainly the body O rings and in the past at the shaft seal. The compressor leaks lead to low charge and they get noisy from lack of steady oil flow... Really low charge and quick clutch cycling with almost no cooling will kill any compressor.
Only way I found to get them to last is recharge the system every year: and then the SOB's leak anyway requiring me to replace them. This is on the R134a. R134a having higher head pressure, esp with the 121 degree weather we have, likes to expand the body and leak the O rings... Lately I have had luck with "New" 4 Season's made in Texas. (I suspect it's lasted just due to low miles every year as Patch is semi retired.) I wouldn't touch a rebuilt R4: You will likely get one of my old ones if you do!
- Staff
- #8
The problem you will encounter is virtually all new compressors come pre-filled with pag, and I don't care how good you drain it, you can't get it all out. Pag and r-12 mineral based oils DO NOT MIX, and in most cases turn caustic over time plugging your system, or eating it from the inside out. You can get the retrofit condenser for a 93 which is basically just a 94 r-134a condenser to replace the smaller r-12 condenser. IF you can find a compressor with no oil in it or mineral oil, I would stay r-12. Otherwise I would convert to r-134 to avoid any oil refrigerant compatibility issues.
At present the cooling system is the only thing I'm not happy with on this truck. I'm not sure why it doesn't cool better than it does. It does not leak, blows out 40% air but you have to leave it on max high to keep from sweating if its very hot at all. It goes through cycle switches fairly often, I've changed 3 in the last year. It does have an issue freezing up. The charge is right, I've cleaned the stack and the evap coil. Nothing helps. I did tint all the windows and put a sun screen on the back glass, before I did that my wife wouldn't even ride with me. I just thought maybe with the compressor change there was some upgrade I could do. Thinking about what WW said maybe it has one of those drop-in replacement refrigerants in it and just going back to real R12 would help?
Coldest system I have is the 1992 that I shoved the Orface tube in the evaporator, parallel flow condenser, no air to oil trans cooler, and factory Harrison compressor. It's followed by the 1993 running industrial Envirosafe with a VOV (It freezes up the evaporator on low/med fan speeds as the pressure switch switches off at -4 with the pressure the industrial replacement refrigerant vs R12/134a same pressure being ~40 degrees). I need a separate controller that has an evaporator probe to stop this. Both have the KD fan clutch and upgraded fans. I just grew tired of the krap R134a just sweating me out in the summer and exploding the system with extreme high side pressures.
Check that the transmission oil flows to the radiator first then that aftermarket oil cooler in front of the condenser. A IR temp gun will show you if the oil coolers are heating up the condenser: The condenser's "red line" is just over 160 degrees so if the oil cooler is 210 it's heating the condenser rather than cooling it.
Check that the transmission oil flows to the radiator first then that aftermarket oil cooler in front of the condenser. A IR temp gun will show you if the oil coolers are heating up the condenser: The condenser's "red line" is just over 160 degrees so if the oil cooler is 210 it's heating the condenser rather than cooling it.
- Staff
- #11
The 93 system if it was a factory r-12 system with r-134a leaves alot to be desired as far as cooling goes. If it's icing up, then either your low pressure switch is bad, or it's over charged. Charging specs are more like guidelines, it's not uncommon to need to vary it slightly, espescially on converted systems. Now if you had a 93 that came stock with r-134a, then it should do alright. 93 was a dual year that could have had either one factory installed. Going to the larger retrofit condenser won't hurt anything. It's just a slightly larger condenser is all to increase the condensers surface area, and allow it to shed more heat and reduce head pressures and increase cooling capacity in the process. The factory 134 systems also got a slightly larger evap to match the larger condenser, but retrofit systems get by with just the larger condenser.
But don't overlook the basics. Is your fan clutch good? Is the stack clean? Is there an excessive amount of bent or crunched fins in the stack reducing airflow? Is the heater blend air door closing off and giving you max cooling? Do you still have insulation on the underhood a/c lines so your not adding unnecesary heat to the system? Is the accumulator insulated? Low pressure switch working properly(opening at 18-22 and closing at 50-55 for r-134, or opening at 25 and closing at 45 for r-12)?
But don't overlook the basics. Is your fan clutch good? Is the stack clean? Is there an excessive amount of bent or crunched fins in the stack reducing airflow? Is the heater blend air door closing off and giving you max cooling? Do you still have insulation on the underhood a/c lines so your not adding unnecesary heat to the system? Is the accumulator insulated? Low pressure switch working properly(opening at 18-22 and closing at 50-55 for r-134, or opening at 25 and closing at 45 for r-12)?
Thanks guys giving me something to think about, it came with r12. New fan and clutch from Kennedy, pulled and rebuilt the radiator so thoroughly cleaned stack. Fins in good shape. New cutout switch. It's standard transmission so no tran cooler. I'll keep checking. I'm thinking could still be a partial stopped up evap coil. I cleaned it, wasn't really all that dirty but could have build up in the fins you can't see I'm thinking. I really don't want to pull the dash.....
Will L.
Well-Known Member
Bypass your heater core temporarily to see how much difference it makes. Make sure the blend door is closing all the way for recirculating mode.
Proper airflow from blower, through coils, and through the vents is a rare issue- but it happens and is almost always overlooked.
I know you said you have he right amount of refrigerant, but that was always a starting point to me. The system works best by the best pressure differential, and sometimes that meant a little less or a little more in the system. It has been too many years, so I can't remember the numbers. But there are charts that based on outside temperature what range high and low side should be in.
Adjust the volume and see what works best in yours. Just like getting rings or bearings inside an engine to the tightest or loosest of the range based on individual use- same for a/c.
A/C is the area of mine that got ruined the worst by fleets, it turned into slap parts and set the automatic machine and walk away. Another use it or loose it skill that I lost somewhere along the way.
Proper airflow from blower, through coils, and through the vents is a rare issue- but it happens and is almost always overlooked.
I know you said you have he right amount of refrigerant, but that was always a starting point to me. The system works best by the best pressure differential, and sometimes that meant a little less or a little more in the system. It has been too many years, so I can't remember the numbers. But there are charts that based on outside temperature what range high and low side should be in.
Adjust the volume and see what works best in yours. Just like getting rings or bearings inside an engine to the tightest or loosest of the range based on individual use- same for a/c.
A/C is the area of mine that got ruined the worst by fleets, it turned into slap parts and set the automatic machine and walk away. Another use it or loose it skill that I lost somewhere along the way.
This is frustrating for me because I own an air conditioning company and understand completely what it takes to cool a space and how a cooling system operates. Once a flooded coil condition exist, adding refrigerant will only result in increased pressures and added load on the system causing poor heat transfer and worse cooling. In an otherwise properly functioning system, freezing is caused by 2 things, 1. a slightly undercharged condition which causes a suction pressure to dip into the range of freezing (temperature and pressure are relative) when still enough refrigerant is available in the evaporator to cause condensation which will then freeze on the coil surface. 2. Not enough or improper air flow across the cooling coil. IE a dirty coil, blocked air flow, faulty blower ect. In an automotive cooling system freezing can also be caused by artificially starving the evap coil at lower engine speeds thus the need for a cycle or low pressure cut out switch. At mean design engine or highway speeds an AC running on HI fan doesn't even need a cycle switch, as if everything is operating properly it won't freeze up.
This system is completely different from home AC systems. One of the best ways to understand the difference is to read about it from one of the R12 FOT designers that later improved the design with a VOV. http://www.imcool.com/articles/aircondition/VOV1.htm
The accumulator and fixed orface tube with a variable speed compressor/cooling fan are the main differences. The Accumulator has around 1/4 LB of liquid in it plus a leakage reserve. So you can over or undercharge a system by 1/4 LB and have it work fine. The undercharge will quickly leak below critical charge and result in poor compressor oil return. These systems cool better on a critical low charge for reasons I am not clear on. As soon as the AC starts running colder I generally evac and recharge it because I know it's low.
The Evaporator has a condensation screen of some sort that can clog with dust/dirt. A R134a cut out switch as noted above is different: so a R134a switch on R12 runs the system colder contributing to freeze up.
The accumulator and fixed orface tube with a variable speed compressor/cooling fan are the main differences. The Accumulator has around 1/4 LB of liquid in it plus a leakage reserve. So you can over or undercharge a system by 1/4 LB and have it work fine. The undercharge will quickly leak below critical charge and result in poor compressor oil return. These systems cool better on a critical low charge for reasons I am not clear on. As soon as the AC starts running colder I generally evac and recharge it because I know it's low.
The Evaporator has a condensation screen of some sort that can clog with dust/dirt. A R134a cut out switch as noted above is different: so a R134a switch on R12 runs the system colder contributing to freeze up.
- Staff
- #17
Also these systems do not run 100% of the time. If the system is low on charge, the low pressure switch shuts the compressor off, so that will not cause it to freeze up. Over charging WILL cause it to freeze up because the pressures will stay to high, and it won't cycle off when it should. Which low pressure switch did you put in it? There is one for R-12, and one for R-134A. The 2 refrigerants have different operating charicteristics, sort of like R-22 vs R-410a. R-134A is a higher pressure refrigerant than R-12, but 134 actually needs to shut off at a slightly lower pressure and come back on at a higher pressure than R-12. R-134 is not as dense, hence why you charge the system to roughly 75-80% of the weight with R-134A as you do R-12, but even with the lower charge volume, it runs higher pressures until the low side gets close to freezing at which point it dips below R-12 pressures. I would put in a R-134 retrofit condenser, R-134A pressure switch, then recharge the system to roughly 85% of the R-12 charge(the larger condenser will take more charge). It will lower your high side pressure allowing it to more efficently transfer heat through the evap and increase your system charge.
JMJNet
Recruit
The low pressure switch on the accumulator is known to fail in this truck more often than people think.
OK AC guys.... is this a good choice for a 93?
http://www.classicindustries.com/product/truck/parts/346002.html
http://www.classicindustries.com/product/truck/parts/346002.html
- Staff
- #20
I have nothing against the R4 myself. From the picture, that looks like an SD5 which is a SMALL compressor, only really suited for a small single A/C system. I believe it was Leroy who put one in his BURB with the ISUZU, and had problems with it not working at LOW RPM's. They're a cheap compressor as they are very popular in add on systems for small classic cars like VETTE's and the like. If it was my money, I would buy a GPD compressor from ROCKAUTO, and call it a day. GPD may be foreign built, but they have earned a good reputation in the auto HVAC field.