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Need help with A/C wiring

TNfarmer

New Member
Joined
Jun 16, 2020
Messages
4
Location
Tazewell , TN
Recently purchased a 2015 259D serial FTL04527. The A/C is not working. The compressor clutch will engage if you jump a hot wire to it. Checked the switch in the cab and it it working. I have replaced the high and low pressure switches and the relay. I have done a refrigerant recovery and charged to the correct amount. I am still not getting any power at the compressor. Anybody have a wiring schematic and suggestions?
 

heymccall

Senior Member
Joined
Feb 19, 2007
Messages
5,349
Location
White Oak, Pa
IIRC, the compressor engagement is power thru the low side switch, typically near the compressor.

#6 should have power on one leg. If you jumper the connector, the compressor should engage.

The condenser fan should come on when AC is switch ON and blower is at any position but OFF. Does the condenser fan come on?

Screenshot_20200616-131013_Chrome.jpg Screenshot_20200616-131043_Chrome.jpg
 

TNfarmer

New Member
Joined
Jun 16, 2020
Messages
4
Location
Tazewell , TN
Low pressure switch does not have any power so jumping makes no difference.

There is no condenser fan or any wires to connect to a fan. Does this machine suppose to have a fan?
 

heymccall

Senior Member
Joined
Feb 19, 2007
Messages
5,349
Location
White Oak, Pa
Does blower motor work (in cab)?
If so, following the 567 wire from blower switch, it goes to AC switch in cab.
Is there power on 567-hv13 in and 520-hv12 out at the AC switch in cab?
Screenshot_20200616-192716_Drive.jpg Screenshot_20200616-192757_Drive.jpg Screenshot_20200616-192448_Drive.jpg
 

TNfarmer

New Member
Joined
Jun 16, 2020
Messages
4
Location
Tazewell , TN
The condenser is in the door.
The blower motor does work and there is power on 567-hv13 in and 520-hv12 out at the AC switch in cab
 

TNfarmer

New Member
Joined
Jun 16, 2020
Messages
4
Location
Tazewell , TN
Thanks to all that helped me on this.

With the schematic I was able to trace down the problem in the circuit. There is a thermostat switch under the cab floor that the AC circuit runs through and the connector was not making good connection therefore breaking the circuit .

After cleaning it up and getting connection , I had power going to the compressor which resulted in AC compressor clutch engaging and VOILA cold air!

Once again , thanks to all for the much appreciated help.
 
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