A/C compressor does not come on or comes on intermittently. When it does come, air coming from vents is very cold.

Checked ground wire to compressor and ohmed out perfect. Just to be on the safe side I soldered a sister wire to it in case there is an intermittent break in it. Reinstalled wire and, compressor does not come on. WIth vehicle running I used my vom and checked the green wire directly where it goes in behind the clutch (somewhat dangerous) and there is 12 volts there!

Why won't this darn thing come on?

If I apply 12 volts directly from the battery to the hot wire then the compressor comes on!

Very confusing to me, what the heck am I missing???????

 

There were at least 4 versions of a/c used in 240's and a couple of versions for the 7's. Not sure about 9's...at least 2. Throw us a bone and let us know the model and year.

 

Sorry-1993 240

 

OK. You have the last year of the 240, and the first and only year that used R134a refrigerant from the factory. Arguably, the most efficient and effective a/c ever in a 240. On the passenger side firewall, you have a silver cylinder, the accumulator. It has a low pressure switch on it. It's possible the switch or wiring is in the process of failing. Remove the switch connector and jumper the two female contacts. This should energize the compressor clutch when the engine is on and a/c switched on. Check voltage on the connector. If you have voltage but no a/c, check continuity of the switch itself. Assuming there is sufficient pressure in the system (which seems likely since it cools) there will be continuity of the circuit. If not, the switch itself is bad. While it is a simple task to remove a and replace, the system needs to be replaced first. So...investigate that first and touch base with us.