Electronic help for A/C system

[matt1517]

This a 95 V6 Mustang 3.8ltr, approx 131k
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Prior to my problem I replaced my a/c system minus the condenser and the evaporator. I put in a new compressor, accumulator, liquid line (with orifice tube). Everything was working fine, even got it to go to 40deg in the afternoon drive. I had the shop do a vacuum and a flush.
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Alright so the compressor decides not to kick on after I turned the switch, but it was working fine hours before. I have checked all the fuses relay's etc. Now, I found a forum were someone said to bypass the low pressure switch and see if it turns on the compressor, well I did this and it worked. So it must be the low side pressure switch right? OK so today I get up go get a new switch and put it on. As I take the old one off I here freon leaking, so I unscrew it faster until it comes off. Now I get the new one and put a new seal on and screw this one in all the way. 'Start the car and the compressor doesn't kick on. Now the freon reading is in the "need to charge zone". We tried the bypass the low pressure switch again and it didn't work this time. I believe I need to check all the fuses again, just to be sure since the bypass did not work.

Also I did a check of the power cable to the compressor, and it reads .0514v when the the A/c is on. The fan does not come on either when I put it on max A/c .The new compressor has the connector on the side facing the fender wall so its a little hard to get to.


I have put 8hrs of work time into this and countless time studying the a/c system for repairs. It safe to say I'm frustrated.

Thanks for any help someone can give.


EDT : checked fuses all are good.

 

[MustangLX-5.0]

Normally the clutch should engage with the harness bypass even if there is no freon in the system. I'm willing to bet your low pres switch was never faulty in the first place. Your A/C stopped engaging the clutch on it's own probably because the freon was getting low. It does this to prevent damage to the compressor and accumulator/drier. If you heard hissing,then freon was definately leaking out someplace. Test for voltage on the low pres harness. You should be getting battery voltage (around 12V). The compressor reads .5V because the switch isn't engaging the clutch. There are generally 2 failsafes. The first is the low pressure switch, the second is a freeze sensing switch. If you don't get 12V at the low pressure switch then you probably have a bad relay. If you do get battery voltage, you may want to check the freeze switch voltage. The freeze switch detects when the evaporator gets too cold or iced up and prevents the compressor from engaging until the tem rises a little. I'm doubting this as you said your fan wasn't even turning on. Was this even after you jumped the low pressure switch that the fan wouldn't turn on? But...regardless you now have to find out where the freon was leaking out. You'll have to get it vaccumed out again (if your freon level went extremely low) or you'll trash your compressor and/or accumulator/drier. Then refill and check for leaks.

I'm not too sure where the freeze switch is located. It may be within the firewall near the evaporator, in which case you'll need to find the wiring to the switch outside the firewall and tap into that. Get the leak problem fixed first. Sounds like it was coming from the accumulator area.

 

[matt1517]

Turns out it was the schrader valve on the high side. The ball looks like it cracked or something. I guess it just unscrews but I'm having a hard time finding the part. I will have to vacuum it and refill it. Though would rather have a shop do the vacuum just 'cause

Hopefully this will fix the problem!