Recharging AC Help!

[4lo co]

My compressor recently seized up on me so I replaced compressor, condenser, drier, expansion valve, and all o-rings. I rented manifold set and vacuum pump and its holding a vacuum.

When attempting to refill the low side pressure shoots up to 100-110 with the vehicle running. I couldn't get the clutch to kick on by filling low side. I turned vehicle off and emptied some into high side at the recommendation of a few posts on here and it helped engage the clutch on the compressor but the low side still shows 100-110 pressure readings when I turn the vehicle on and clutch engaged.

Am I missing something? Could it be a switch or relay?

 

[Michael Hanson]

Hi, Did you flush the system ? Mike

 

[4lo co]

Hi, Did you flush the system ? Mike

I did flush the system.

 

[Michael Hanson]

Hi, Sound like the switch in the engine compartment next to the dryer condenser is not hooked up. Mike

 

[4lo co]

I'll go check and let you know what I find. Thanks for suggestion!

 

[4lo co]

I'll go check and let you know what I find. Thanks for suggestion!

 

[Michael Hanson]

Hi, I'm going to have to go ,but I'd check the low pressure switch real carefully. Since it's also called the gas leak detection switch it may have failed leading to your compressor burning ,seizing up due to low refrigerant. Mike

 

[Landseer]

Not related to your problem, but did you add PAG oil when you replaced the condenser, drier, etc.?

 

[BILT4ME]

What year truck and what version of freon?

 

[Nostradamus]

There is usually a high pressure and a low pressure switch to protect the compressor from being overloaded and/or run dry of oil (oil circulates with the refrigerant). When the system is uncharged or low on charge, the low pressure switch needs to be bypassed in order to engage the compressor clutch (by connecting the wire coming from the compressor where the LP switch plugged in to the + side of your battery - I use a 20 in piece of wire w alligator clips on each end). Once the clutch is engaged (you'll hear it click), on the manifold gauge set, you should open up the low pressure side knob and make sure the refrigerant source knob is open, and the suction side of the compressor (low side) will draw the refrigerant in. Let it keep pulling until you get the right low and high side pressure readings that correspond to your refrigerant type (most likely R134A) and ambient temp. I'm a little old school and usually like to see the sight glass w no bubbles, but the pressures should be good enough on their own. Then pull the jumper off your low side switch and plug it back in to the harness and make sure the compressor still cycles.

 

[4lo co]

Hi, Sound like the switch in the engine compartment next to the dryer condenser is not hooked up. Mike

The switch was hooked up. I removed it to replace it and see if that's the problem.

 

[4lo co]

There is usually a high pressure and a low pressure switch to protect the compressor from being overloaded and/or run dry of oil (oil circulates with the refrigerant). When the system is uncharged or low on charge, the low pressure switch needs to be bypassed in order to engage the compressor clutch (by connecting the wire coming from the compressor where the LP switch plugged in to the + side of your battery - I use a 20 in piece of wire w alligator clips on each end). Once the clutch is engaged (you'll hear it click), on the manifold gauge set, you should open up the low pressure side knob and make sure the refrigerant source knob is open, and the suction side of the compressor (low side) will draw the refrigerant in. Let it keep pulling until you get the right low and high side pressure readings that correspond to your refrigerant type (most likely R134A) and ambient temp. I'm a little old school and usually like to see the sight glass w no bubbles, but the pressures should be good enough on their own. Then pull the jumper off your low side switch and plug it back in to the harness and make sure the compressor still cycles.

I jumped the compressor. Clutch kicks on but pressure doesn't go down on the low side. Like it's not taking in the freon.

 

[4lo co]

What year truck and what version of freon?

92 80 series. R134

 

[4lo co]

Not related to your problem, but did you add PAG oil when you replaced the condenser, drier, etc.?

I did. Added 7oz total.

 

[BILT4ME]

How much freon have you been able to get into the system?

 

[brianh699]

Some good info in this thread AC won't take freon
Vapor charging on an empty system can be difficult, I find it works better to charge as much as possible as a liquid when there is a vacuum (engine not running, so as not to damage the compressor).

 

[4lo co]

Some good info in this thread AC won't take freon
Vapor charging on an empty system can be difficult, I find it works better to charge as much as possible as a liquid when there is a vacuum (engine not running, so as not to damage the compressor).

Brian,
I've read that thread a few times and tried to do that but not sure if I'm emptying as a liquid correctly. What's the exact process you do to empty it into the system as a liquid with the engine off?

 

[4lo co]

How much freon have you been able to get into the system?

Maybe 3/4 of a can?

 

[brianh699]

Brian,
I've read that thread a few times and tried to do that but not sure if I'm emptying as a liquid correctly. What's the exact process you do to empty it into the system as a liquid with the engine off?

Turn the can upside down and open the valve for the high side of the system, if you're using small 12 oz cans it should take a full can. After that charge as a vapor (can right side up) through the low side(engine running) until you've got the right weight of coolant in the system. This is a r134a conversion PDF from Toyota which will give you proper weights for your model. https://www.google.com/url?sa=t&sou...FjAAegQIABAB&usg=AOvVaw3Y0atamS9nurAf76p4ki5h

 

[4lo co]

Turn the can upside down and open the valve for the high side of the system, if you're using small 12 oz cans it should take a full can. After that charge as a vapor (can right side up) through the low side(engine running) until you've got the right weight of coolant in the system. This is a r134a conversion PDF from Toyota which will give you proper weights for your model. https://www.google.com/url?sa=t&sou...FjAAegQIABAB&usg=AOvVaw3Y0atamS9nurAf76p4ki5h

Thanks a bunch for the advice man! I'm going to go ahead and try this ASAP. I'll let you know how it goes.