07-23-2013, 04:45 PM
Join Date: Mar 2013
Location: Syracuse, NY
What I Drive: 2001 Black Focus SE Wagon
FF Reputation: 1
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Originally Posted by amc49
The diode looking part IS the thermal limiter, if truly getting less than one ohm across connectors the part IS GOOD. You will get infinity if it is melted open inside. Thermal is supposed to save the plug connection but rarely works, the plug melts instead. Thermal limiter merely sits there until melting time and affects resistor coil in no way.
Stick part back in there and use it.
I rebuilt my melted resistor and used the same air coil but ditched the thermal, it works fine. No need for the thermal if it's not going to work anyway. Made up positive screw connectors with nut and bolt to spread temp absorption a bit. Bigger connectors too.
X2, my_beautious, the fuse should pop-
this is incorrect..............
'No damage or over current situation will occur'
If someone ties those two wires together by simply snapping a quick connect double ended male spade in between them to preserve wires till buying a new resistor, I can practically guarantee some melting there. Those two spades are much smaller than any others used in the system, why they melt at 30 amp power all the time. Going to 50 amp will be melt city. Look at all the other fan wiring connectors used, they are much bigger than those two, engineering messed up there.
Is it the thermal limiter could still be bad but would only be bad under full load? In my field I need special high current testers as certain parts will not not test bad under the low current of a standard multimeter?
Originally Posted by whynotthinkwhynot
You can bypass the low pressure switch on the AC in order to make the fans run, you can also bridge the output of the low speed relay and high speed relay so that the fan will run in high speed when low speed is called for. These are inexpensive methods of fixing the bad resistor.
To bypass the low pressure switch: first unplug the AC compressor clutch so it won't run. Second, find the low pressure switch which is located on the accumulator under the passenger fender. You will have to jack the vehicle, pull the tire, and the inner fender plastic. Unplug the switch, and bridge the 2 points on the switch plug with some solid wire. Tape to hold in place. Now the fan should come on when the AC button is pushed.
To bridge the relays you will need to remove the underhood fuse box so that you can get to the bottom side of it. This is the best place to do this, but you could also do it at the fan resistor plug-in. I would bridge the coil wires. Look at the wiring diagram on the side of one of the relays. You'll see two wires at the points of what is drawn as a box with a line through it- that is the magnetic coil for the relay. IIRC these are 85 and 86. Flip the relay over, and you will see numbers beside the pins. Now unbolt the relay box, and look for the corresponding wires for that relay under the box. You should only see one wire- the other is a ground and is wired internally. Tie the wire from the low speed fan to the high speed fan. This can also be done with very small gauge wire from the top with both relays removed- but then I don't know which point is ground and which point is hot. You don't want to tie a hot to a ground or there will be a blown fuse which could take out all the relays bringing the car to a halt. You will have to use wire small enough to be able to re-insert the relay. Do not use this method to tie the output wires together- those are high current, and using a small enough wire to allow the relay to be pushed down will cause excess heat and damage the relays or the box.
You can do this at the fan resistor plug. One hot goes through the resistor for the low speed, and the other hot goes straight through to the fans for high speed. Tie those 2 wires together, and you've bridged the outputs. Now the fan will operate on high speed when low speed is called for. No damage or over current situation will occur, you just simply won't have a low speed, and you won't be running the fan continuously like some goofball who installed a switch in place of the controls Ford uses.
The fan resistor is $45, and that fixes the problem also. I'd have to look into your overheating threads to figure out if this is causing your overheating. Engine cooling fan problems only cause overheating in stop and go traffic, and low speed traffic below 45 mph or so. Above those speeds, the fans don't operate or do anything anyway because there is plenty of air being forced through the radiator by simply moving. If you are overheating on the highway, then you have another cooling problem not related to the fans.
Wow - whatever happened to the old days of everything for the A/C being accessible under the hood? The bypassing of the resistor has been called into question so I will have to check into that.As for my overheating problem - yes it only occurs in stop and go traffic and I have verified the fans do not start. I had a previous overheating problem after the heater bypass broke but it was apparently air trapped in my system ( as someone suggested) as it eventually worked itself out