Ford New Holland 7740 Ac Wiring Diagram
| | |
SEARCH MANUALS 
Search This Message Board:
ford 7740sl a/c problem
| charlie cooper | Hi my a/c clutch does not cut in ,fuses and relays are good.No power at the lo pressure switch.If I put power to one side of the lo pressure switch it will cut in and cools very well.I don't have a wiring diagram,please help |
| mike | There are two potential causes. The first to check is the tempreture control switch. The center switch in the overhead console. There are four wires going to it. When the fan is on and the switch turned on there should be power at the two wires attached to the back of the switch. The other two wires attach to the side of the switch. Follow these two wires to the connector, about 6 inches from the switch, and check that you have power on each side of the connector. If you have power on each side on the wire connecter than all that is left is the thermostatic switch. It is a little black box attached to the back of the box housing the fan, evaporator and heater core. It is directly in front of the low pressure switch and down a few inches. It has a capillary tube going into the evaporator. While you can see the switch easily you can not replace it easily. You just about have to remove the headliner to replace it. The lower mounting screw is not accessable from above and the tube goes across the air box through several wire holders and clamps. |
| Charlie | Sounds like the thermostatic switch (thermistor) all right. I replace the damn thing in my 7840 SLE about every 1000 hours, they must be making them in outer Mongolia or something these days. The easiest access is to take out the four screws holding the roof hatch down, you can look straight in on it. All you have to do is plug in the new switch and run the capillary tube into the evaporator. |
| Lester Burns | where is the fuse and relay been trying to find a fuse panel layout with labels but not having any luck. |
| mark davis | To Charlie: I have a ford 7840 and I want to know if you can get the thermostatic switch some where other than the ford dealership. Also I bought one a while back and had to swap the plug from the old one to the new one so it would pulg in correctly is that right. |
| Nelson | My 7740sl was acting the same way as Charlie's. I jumped power to low pressure switch - A/C started working although I can't control the temperature. When I turn the fan off the A/C clutch does not dis-engage. Does anyone know if it will damage anything to run like this ??? ( Fan on ) |
| larry kehl | i have ford 7740 sle with similar problem a/c works fine for hour or two then quits cooling for hour then starts working again for a while. have the tempature switch replaced couple of times but don't help, please help |
| Jayson | Our AC on our 1995 7740 (4000hrs) stopped working also, but the fan still blows. (After the fact we learned that it had been coming and going for some time) First we checked the compressor and no power going to it. Next we checked the temperature control switch in the cab and had power going in and coming out with the switch on, although no hint of power at the two wires going into the side of the temp control switch. After reading Charlie post we did go ahead and remove the thermostatic switch and have one on the way. Found it for $80 shipped off the internet vs. almost $300 at the dealership. When removing the capillary tube we had to remove the lid to the box where you can see the evaporator. There is rotten deteriorated foam that appears to be clogging some of the evaporator fins. Before it went out completely it had good cold air flow so we're unsure if this blockage contributed to the problem? What's everyone's thoughts on the thermostatic switch being the issue? |
Post a Followup
Source: http://www.ssbtractor.com/wwwboard/view_all.cgi?bd=ford&msg=15770
Posted by: airhomeair.blogspot.com