CAT 262D skid steer AC

[That_guy_over_ther]

Hey, I have a CAT 262D skid steer and the ac compressor is not kicking on. I checked power to the compressor and wasnt getting anything so i checked the relay and still wasnt getting anything. I checked continuity between the relay and the other end of the harness and had continuity. After messing around with plugs probing and checking voltage and continuity i rechecked the relay and had power on one side. The other side of the relay is still dead. Where should i go from there?

 

[heymccall]

The compressor will not engage if the refrigerant level is extremely low, or empty.
Do you have access to refrigerant gauge(s)? Even the single shot can with the colored gauge on it is good enough to start with.

As for the relay, engine running, relay removed, AC on, there should be 12 volt in two of the 4 socket holes.

 

[That_guy_over_ther]

I can get access to gauges yes and i tested it with power on not running and only had it on 1 socket. I traced the wire back to the ecm. the prong from the ecm is giving 6.1 volts but if i plug the main harness back in, prode the back of the wire, and check it from there to the other end of the harness im only getting .02 volts. does this indicate a break in the wire between the ecm and harness plug?

 

[heymccall]

A serial number would help get you a schematic.
Not running typically won't engage the compressor on a Caterpillar.

Bypass the compressor relay by jumpering from 30 to 87. That will emulate a latched relay.
Does the compressor now engage?
Make certain that you are on the correct pins.

 

[heymccall]

Wire 125 (orange) should have power at key on.
Fuse A8 (20amp) is suspect if orange has no 12volt.

 

[That_guy_over_ther]

The fuses were good and yes that wire has power the A510 wire is without power. Thanks a lot for your help I'm not much of an electrician

 

[heymccall]

Next, put relay back.
Now jumper the low side switch, making sure that the connector you are bypassing has an orange and purple wire, on the refrigerant line in the trunk.
Location circled at (108) in the picture.



That engages the compressor, either the refrigerant has leaked out, or the switch is bad.

 

[That_guy_over_ther]

Ill do it. Thank you so much

 

[Arny L]

The fuses were good and yes that wire has power the A510 wire is without power. Thanks a lot for your help I'm not much of an electrician

If A510 is without power, that is your problem. Terminal 86 comes on with key switch, terminal 30 should have 12v always.

 

[That_guy_over_ther]

that should lead to pin 77 on J1 on the ECM. I probed this wire from the back of the ecm plug to the other end of the cab harness and got .02 volts which isnt right so i unplugged the ecm harness and the ecm is putting out 6.1v on that pin. does this mean the problem is likley a break in the wire between the ecm cab harness and the ac harness. Im not sure im explaining that well im kind of new to this

 

[That_guy_over_ther]

Also the diagram of the relay above shows the main power running through the fuse. my key switch is ran to fuse and the constant is ran to the ecm is that important?

 

[That_guy_over_ther]

since the constant is ran to the ecm could a bad pressure switch or low gas level create an open?

 

[Arny L]

Did you verify 12v at terminal 30, with relay removed. Terminal numbers are shown on the relay. Start there. Then turn on ign key, and verify 12v on terminal 86.

 

[That_guy_over_ther]

Yes I had power on 86 nothing on 30

 

[heymccall]

Not sure, as you didn't share serial number.

 

[That_guy_over_ther]

Oh I’m sorry DTB09772

 

[Arny L]

Then you need to find the fuse that protects that circuit. A5 10amp, Power Port, as diagram shows,

 

[That_guy_over_ther]

Ok ill check that. Thank you for all your help I really appreciate it