360d/540GIII AC/Heater not functioning

[TheDirt]

just curious if anyone has had experience with losing power to blower, temperature selector and defrost/ac switch all at once. happened to me this morning, fuses appear fine, relays i checked.
wondering if a wire between the relay and the switches is going bad. I have noticed that the blower will weaken throughout the day, running heat or AC. I don't think the blower is bad, it seems there is just no power reaching any of those functions. 
Thanks!

[kiko]

The the load wire that comes out of the blower relay will get heat damaged over time creating the low voltage situation. Often you can see this by removing the relay where you can see discoloration of the spade receptors and sometimes distortion of the plastic.  The fuse panel is modular and be partially repaired but is difficult . The way I have solved that issue is by cutting the wires loose from the back of fuse /relay board and running to a continuous ford type relay mounted to metal wall behind the fuse panel.

[TheDirt]

This is great information, Kiko, thanks!
there is a heater blower relay that must have been bypassed because it's just gone now, definitely looks like it got hot at one time, I will dig into that tomorrow and try to figure out where they went with those wires, if i can. The Relays I tested today were for the high speed blower relay and the purge blower relay. Would one of those be sending power to the temp selector dial, fan speed dial and defrost/ac switch? seems like theses must all be tied to the same relay.
thanks again.

[TheDirt]

tore back into it this morning and turns out they had re located the heater blower relay to behind the dash monitor/screen. not the first place i would have looked but im glad i did. that relay was bad, switched it out and back in business. Thanks again Kiko!

[kiko]

 

[TheDirt]

Well, that worked for a while, then the relay and wires started getting hot again. sort of functioned intermittently if i wiggled the wires around and and tapped on the relay, then the relay went again. now im looking to do a more permanent upgrade.
KIKO, I was hoping to get a little more detail on the upgrade you did, the relay you used was a continuous type, do recall amps? did you upgrade any wiring coming into/out of the relay?
thanks!!!!

[kiko]

NAPA part # PHI 54140.

[Firewoodjoe]

Those are prone for that. Just keep a new relay in the machine and don't run the blower on high. It will last longer. 

[TheDirt]

Thanks Kiko, I ordered the continuous relay and re routed the wires to it, mounted on the firewall behind the computer. it works great, it does still get a little hot but the wires aren't melting and relay can handle it. like you said firewoodjoe, its probably best to not run it on full blast all day, and not usually necessary once the cab reaches the right temp 

[Tacotodd]

Just remember, there is no difference between a relay and a solenoid. Just get a continuous duty solenoid if you have the room for it and your troubles will be over. They are made for just such instances.