08-28-2009, 07:26 PM
Join Date: Jul 2009
I am going to try to make this simple....yeah right..........
There are a few things to look at...
A ref. system is designed with safety switches to protect the system from failure. The switch mentioned above is called a loss of charge switch and will kill the compressor when the pressure gets to low.
Also the compressor has a overload switch that will also kill the comp. when it gets hot. The reason it gets hot is that it requires the cool ref. to do so. If it is low on the ref. of choice it will over heat.
There may also be a high pressure cut out switch that will cut the power off to the comp. if the condenser is dirty the head press. will rise..
If you guys are still with me... let's get into this thing...I hope I have been simple enough
The first thing I would do is get a dummy gauge (the one you would find that comes with a can of R 134a, if the system is or has been retro from 92'. If it is older than 92' and not been retro, you will need gauges for R12)
Install the gauge on the suction port ( larger line off the comp.) Have some one raise the RPM's to 2000 RPMs Then check the reading, the gauge will tell the first symptoms. (I do not have this gauge, but it should go to the green while the comp. is running. (12 O'clockish) It should drop below that for a few seconds than rise a few degrees.
Now we can start...
If it stays below the green mark you are low on ref.. The gauge will slowly drop from there as the capacity of the evap. coil is not being used and the system will slowly ice up. Causing the system to start icing up and the pressure to drop, the loss of charge switch to open. Also the compressor might get hot and the over load might kill it.
If your condenser is dirty or being low on ref., or the cond. fan has stopped running, could cause the high pressure switch to open.
I have tried to explain this before but cannot figure out how to put this into simple form for you guys to understand. I have left you with some of the symptoms and safety's that will cut things off. PM me if you want some more help. Some of this stuff kills me to explain on line. Refrigeration is not easy to comprehend and is hard to sum up in few words.