I'm bench testing a new replacement AC clutch coil before installing it in a van. The coil was placed on a large iron girder and when power (14V from alternator and drawing about 3.5A) was applied the coil magnetized and after a minute or so was very hot to the touch although the 14 gauge jumper wires were not hot. This was not engine compartment heat but from the coil itself- is this normal?
Thanks

 

No it should not get hot.

 

Sir, Could you please tell me if this is from "hands on" experience or theory? On an electronic forum the theory based answers are all over the place and I've been looking for a source based on experience. It has also been suggested to me the fact that the coil was bench tested without placement on the compressor core shaft may be the reason for the heat. This thing gets hot almost to the point it could blister a finger on it for like 5 seconds and I know there are very small wires with only shellack insulation inside. I was getting 12.8V on my test and drawing 3.6A. Service Manuel lists draw at 3.5A so that's not the problem. Resistance through the unplugged coil is also good at 3.5 ohms.
I'm thinking I should send it back for a replacement (EBay) before installing it and frying it.
​​​​​​​Thanks

 

I can speak from experience with the coil installed on the compressor. As long as the resistance of the coil is between 2 & 5 ohms the coil is good. There could be some merit to the argument that the body of the compressor will dissipate most of the heat.

 

Thank you,
The heat had me concerned about a short but I get it- at a measured resistance of 3.6 ohms I don't have a short. And hot to touch does not mean hotter than an OK operating temp.