Good evening, fellow DIY'ers!
I have some questions concerning condenser fan motors. I have a Heil/ICP Combination Gas/Electric HVAC unit (Model# PGAA36D1K1) that stopped cooling in the middle of the day. It does blow air from the air ducts/registers, but that air is very warm and uncomfortable.
I went outside and found that the condenser fan had stopped and the unit was making a very loud humming noise. I quickly pulled the disconnect and unscrewed the front panel. One of the terminals on the dual run capacitor was burned, and horrified, I ensured it was discharged and removed it. I then remembered the unit used to make a loud "BRRITTTTT!" sound each time it was started after a long rest. So I figure the fan motor was on its way out then and is finally dead now. So I remove it too.
The good guys at Graingers look at the old fan motor and capacitor, test the capacitor (it is bad), then give me a "compatible" universal fan motor and capacitor:
** It also has a 2 inch shaft and only three wires coming from it.
35+5uF 440V 50/60HZ 70C (Part# HQ 1053068 AX)
** 6 inch shaft, seven wires, and says "7.5 MFD 370 VAC CAP REQUIRED" on its label.
35+5MFD 440VAC 60/50HZ (Dayton Part# 2MEJ5)
I am concerned with a few things.
1) Are the new motor's higher AMP draw and lower RPM detrimental to the system?
Granted, it is just a 45 RPM difference, so I'm guessing that is okay. But the AMP draw is quite a bit more than original. I've read that AMP draw of a new motor should never exceed 25% more than original (fact# 3 on page 20 of http://www.fasco.com/pdf3/fasfacts.pdf
). That means the 1.4 AMP motor should at most be replaced with a 1.75 AMP motor... right?
I also noticed that I could buy online an OEM direct replacement (A.O. Smith Motors part# 645A) with 1120 RPM and 1.2 AMPS, but it will take forever to get here. I'm assuming it is okay to go lower on the AMP draw, but not okay to go much higher... Is this correct? Or is it okay, so long as the capacitor is rated properly for the motor?
2) If the higher AMP rating is ok, then is the capacitor they gave me adequate? Should I have been given a "35/7.5 MFD, 440 VAC" unit instead of another 35/5 440?
In fact, what will happen if I use the lower rated capacitor with the motor that says it requires a 7.5MFD? Will it overheat or provide less HP or RPM?
3) Is there any way to safely test the old motor?
When I removed it, the shaft turned very easily with my hands. I realize motors can fail in other manners than just seizing, but is there a way to safely test it to be sure it's actually bad, and it's not something else like the contactor?
Thanks in advance! I'm sweltering here and don't want to blow up anything, so I'll wait til I hear back to do anything further. Definitely looking forward to your replies!