So I need some help getting my a/c to work properly. I recently converted my 87 4runner over to 134a, my compressor clutch engages when I turn the a/c on but I could only get a can of oil charge in the system. When I tried to put some freon in the system I cant get it to pull in, does this sound like a bad low side pressure switch? I really don't know too much about A/C systems so any help would be appreciated.

 

Are you charging on the low side? If there was no freon in the system the clutch should not have engaged without it being jumped. If you would, list the steps you did when you converted.

 

I didn't clean the system when I converted it, all i did was take out the schrader valve ( only a little bit of oil came out, no freon just some hot air) then put on the 134a converter on the low side, the port to the left on the compressor. I then put half a can of freon in,then an oil charge. Now I can't get anymore freon in the system, its almost like there is too much pressure in the system, I am using a cheap autozone gauge/tube and its reading low pressure though .

 

If you didnt have the system evacuated and vacuum pulled then you have air and incompatible oils mixed in the system. These are not good things. The small hoses they sell at autozone are called suicide hoses, it takes a long time to get freon in a system with those. You can try shaking the can but dont turn it upside down you dont want to dump liquid freon into the compressor.

 

uh oh, I did hold the can upside down and shake it.. what happens if liquid freon gets in the system? Also where is the low side pressure switch so I can test it

 

How long is the hose your using? The reason you dont want to hold the can upside down is because it puts liquid freon into the compresser which can hurt it. You have liquid freon in the a/c system just not in the compresser. The compresser pumps freon when its in its gas/vapor state. The low side switch in located behind the glove box I think. What pressure was the gauge at when you were trying to add freon?

 

the gauge was in the red as in high pressure around 120psi. It couldn't have that much pressure in the whole system though because it only has 6oz of freon in it. Is there anything that would stop the freon from circulating threw the whole system, like a pressure switch or something? The air is blowing cool but definitely not cold like a full system would. Thanks for all the help

 

If the gauge was hooked to the low side and it read 120psi with the clutch engaged thens somethings wrong, thats a pressure you should see on the high side. The air left in the system from not vacuuming it down will throw your readings off and cause the pressure to be higher. You could have a restriction in the system somewhere or your expansion valve could be stuck.

 

Alright I think I am going to take it to a buddy's shop and have it vacuumed then try it again. Thanks for the help

 

That sounds good. I think these systems take 2 1/2 cans of 134a but I'm not sure. Its 80% of how ever much r12 they take.