I have a 92 Fox coupe that has been converted to 134a.I bought the car and the A/C clutch was frozen.I already have purchased a new one and it's on the way.I was wondering if there is a difference in clutch sizes for the r12 system as opposed to the 134a conversion?Should have maybe asked this b4 I ordered.
Any help is greatly appreciated.J
A/C clutch??
- Thread starter 92NotchJS
- Start date
bill302
Active Member
both types use the same compressor the only difference is the oil and coolant type. when a system is changed from r12 to 134a no changes are made to system the only thing done is system fully evacuated of r12 oil and freon,with a filter and dryer replacement and recharged with 134a.
The A/C clutch is about $100 new or you can buy a compressor from the junkyard with a working clutch for about $50. The puller is about $16 if you have to buy one, Autozone will rent you one for free.
The clutch hub is usually what fails, the rubber shock damper shears off from the steel hub and plate. The pulley turns, but the hub doesn't when you power up the A/C. The hub comes off without much problem if you have the puller. You don’t have to do anything with the refrigerant (R12 or R134a), you can replace the clutch without draining and refilling the system.
A few simple electrical tests are advised before popping out the wallet to buy a clutch assembly. With the engine running, use a test light connected to the 2 wires on the A/C clutch harness to make sure you have voltage when you turn the A/C on. If the system is low on refrigerant, the clutch will not engage (safety feature, keeps you from burning up the compressor due to no oil). There is an aluminum canister on the firewall with a large hose leading to the A/C compressor. There is a pressure switch on it with a 2 wire connector: pull the connector off and jumper the wires. The compressor circuit will power up, and the test light will light if the electrical circuit is good. This test is also a good way to check the compressor & clutch if the system is low on refrigerant. You can jumper the wires and the compressor will turn if the clutch is good.
The clutch hub is usually what fails, the rubber shock damper shears off from the steel hub and plate. The pulley turns, but the hub doesn't when you power up the A/C. The hub comes off without much problem if you have the puller. You don’t have to do anything with the refrigerant (R12 or R134a), you can replace the clutch without draining and refilling the system.
A few simple electrical tests are advised before popping out the wallet to buy a clutch assembly. With the engine running, use a test light connected to the 2 wires on the A/C clutch harness to make sure you have voltage when you turn the A/C on. If the system is low on refrigerant, the clutch will not engage (safety feature, keeps you from burning up the compressor due to no oil). There is an aluminum canister on the firewall with a large hose leading to the A/C compressor. There is a pressure switch on it with a 2 wire connector: pull the connector off and jumper the wires. The compressor circuit will power up, and the test light will light if the electrical circuit is good. This test is also a good way to check the compressor & clutch if the system is low on refrigerant. You can jumper the wires and the compressor will turn if the clutch is good.
Order the clutch for your stock application. The only thing commonly changed from a r12 to r134a coversion is the refrigerant and oil.92NotchJS said:I have a 92 Fox coupe that has been converted to 134a.I bought the car and the A/C clutch was frozen.I already have purchased a new one and it's on the way.I was wondering if there is a difference in clutch sizes for the r12 system as opposed to the 134a conversion?Should have maybe asked this b4 I ordered.
1) Yes, the clutch is the same
2) That's not really a true statement. To do the conversion properly, you must also swap out all the factory O-rings (black in color) for the proper 134a O-rings which are green. The green O-rings are designed to work with the smaller molecules in R134a. You need to pull a deep vacuum on the entire system for a minimum of 45 mins. With your A/C manifold gauges still connected, close the manifold valve connected to your vacuum pump. Let your system sit sealed for at least 24 hours to make sure you don't have any minor leaks (48 hours is even better). If you see any type of raise in your vacuum gauage reading....then you have leak (most likely an O-ring) that needs to be corrected before you fill the system with R134A. If your system is tight and holding vacuum. Then your ready to add your 134a gas. You also need to adjust your low pressure cut-out switch (on top of the accumulator) after converting to 134a. If you take off the electrical connector, you will see a small screw inside. For R12, that switch should be adjusted to turn off the compressor when the low side pressure reaches 25PSI. For R134A, it should be adjusted to cycle the compressor at 21-22PSI. Turning the screw counter-clockwise lowers the pressure cut-off point. Turning it 1/4 of a turn lowers the point by ~3 PSI.
bill302 said:
2) That's not really a true statement. To do the conversion properly, you must also swap out all the factory O-rings (black in color) for the proper 134a O-rings which are green. The green O-rings are designed to work with the smaller molecules in R134a. You need to pull a deep vacuum on the entire system for a minimum of 45 mins. With your A/C manifold gauges still connected, close the manifold valve connected to your vacuum pump. Let your system sit sealed for at least 24 hours to make sure you don't have any minor leaks (48 hours is even better). If you see any type of raise in your vacuum gauage reading....then you have leak (most likely an O-ring) that needs to be corrected before you fill the system with R134A. If your system is tight and holding vacuum. Then your ready to add your 134a gas. You also need to adjust your low pressure cut-out switch (on top of the accumulator) after converting to 134a. If you take off the electrical connector, you will see a small screw inside. For R12, that switch should be adjusted to turn off the compressor when the low side pressure reaches 25PSI. For R134A, it should be adjusted to cycle the compressor at 21-22PSI. Turning the screw counter-clockwise lowers the pressure cut-off point. Turning it 1/4 of a turn lowers the point by ~3 PSI.
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