1990 GMC Sierra A/C Problem

[joeg2246]

My 1990 Sierra has an aftermarket A/C system installed in it. I just got the truck and noticed that the blower motor only worked on high. I did some research and replaced the fan resistor. Thought I had fixed the problem only to now it blew the fuse on high speed. The fuse I am speaking of is an inline 30 amp fuse that comes from the junction block in the engine compartment through the firewall to the compressor relay. I replaced both of the relays. It seems like one is for the compressor and the other is for the high speed selection for the blower. There are 2 lines of power for the blower, one for the high and the other for the low and medium. The wire for the low and medium was pinched and shorted to ground. I noticed that and fixed it.
So now I have replaced the blower motor, the blower resistor, inline fuse holder (first one melted due to the short) and both relay's.
I ohmed the switch and it seems to be doing what it is supposed to do. I did measure the clutch wire for the compressor and it measured out at less than 1 ohm. I think that is a little low but not real sure. The power for the clutch comes through that relay from the power wire where the fuse that keeps blowing.
One more thing the fan will run on high forever without the clutch being engaged but it blows as soon as the power is applied to the clutch.
I think I know the answer to my problem but would like a second opinion.
Thanks for any help!!!

[SierraK1500]

Seems your A/C Clutch is on the same line as fan and is pulling too many amps, or the clutch is shorted.