View Full Version : Potential Relay not staying open

28-10-2003, 01:48 AM
I just got a new 3/4 HP 120volt compressor for a freezer. However the relay tries to close every 2 seconds or so over and over again. By doing this it continually is trying to engage the S side of the compressor. There is a Start capacitor before the relay but it doesn't seem to keep sufficient voltage for the relay to stay open.

The relay is rated is listed on this page.

http://www.jard.com/prelays.htm model jpr-63

Please help.


04-08-2005, 06:04 AM
Relays ( as we are talking potential type ) will short cycle for the following reasons,
1- incorrect application
2- low EMF (counter EMF)
3- not positioned correctly (some are positiom sensitive)
4- voltage problem from source or through the OLD thermostat.
5- bad (?) compressor windings
6- poor electrical contacts/path

and there is always the famous- it came that way, and is defective.

05-08-2005, 07:11 PM
Mr, Lab.
I thing U dont know any thing about compressor ?
better contact a tech and get it tested!
In my opinion,
a, faulty starting cap,
b, faulty olp,
c, compressor motor is short,
beni joseph.

05-08-2005, 08:11 PM
I will have to agree with Mr Joseph on this one.

I presume olp is over load protector?


05-08-2005, 08:14 PM
Potential relays are wired in parallel with start windings and are therefoe controlled by the back EMF of the start winding. You aparently have a mismatch If the start winding or the capacitor was defective you not be able to start the compressor. P.S. the start cap has nothing to do with the relay its function is to increase the phase shift between the run and start windings