Combines m2 blows 20 amp fuse when ac is turned on

[Hyper_Harvest_II]

Could be one of several things. Are the clips that hold the fuse in place loose or rustyIJ This will build resistance and cause fuse to blow. We have moved this fuse down to an open slot below existing fuses and hooked wire to that slot to get a tighter and cleaner fuse slot. If there is nothing wrong with fuse holder then how does the cab blower soundIJ Smooth as silk when running and coasts to a stop. If blower seems to be making noise when running or stops right away when turned off then I would suspect blower motor to be causing extra drag and creating fuse to get hot and blow. You could try to blow fins in squirrel cage fan out as they can get built up with dirt and throw fan out of balance. Also have seen mice chew on wires in behind RH corner console and also up by blower motor. Also check ground wire for blower motor as it can also be rusty and causing extra resistance. You could also try a 30 amp fuse and then check wiring in different areas to see if you can find heat build up where the problem lies. Good luck, Hyper Harvest II

 

[tractorjockey]

have new blower motor, have checked the other and could not see anything obvious. fuse connector was a little loose. could it be the compressor clutchIJ

 

[Hyper_Harvest_II]

Is the system cooling properlyIJ It is possible that if system is low that compressor is pulling more amps if system is low which could cause fuse to blow. Does it also blow a 30 amp fuseIJ Do you have any gauges to check pressuresIJ Is this a R12 system or has it been converted to R134aIJ If it is still an R12 system then it may be time to covert to R134a. Hyper Harvest II

 

[tractorjockey]

Yes, it does cool good,haven't tried the bigger fuse yet.134 system, use sight glass and low side guage to check pressure when adding a can.

 

[Hyper_Harvest_II]

It would be nice to have a set of air cond. gauges to monitor both high and low pressures. We had a tractor the other day that was running 350psi on the high side and climbing. Found that the condenser fans where not running. Which brings up another question, is the condenser cleanIJ A short jumper wire from starter to air cond. compressor clutch could be used to see if jumper wire gets warm when runnning system. The ultimate would be a amp draw tester to determine what compressor amp draw is running. Three to five amps should be all that it takes to lock clutch and run compressor. Hyper Harvest II

 

[tractorjockey]

Ok thank you for your help. We are starting to cut today near wichita.

 

[R_O_M]

With the AC mounted down the back together with the batteries, there is a lot of wire to carry a fair current between those batteries, up to the cab switch and back down to the AC compressor. Placing a relay into the system to carry the heavy current load over only a short distance from battery to AC compressor reduces the current into and out of the cab AC switch and wiring system down to milliamps to switch the relay and will help overcome any serious resistances that have arisen in the wiring loom over the years. Relays for the condenser fans and the cab fans also help a lot rather than relying on [ overloaded IJ ] cab switches and long wiring looms to carry the full current load.