Raypak R5350TI-E heat pump melting one of the spade connectors between the relay (with the incoming 240V) and the capacitor.

[micheldb]

Strange question but it's the second time that one of the wires that's between the relay (with the incoming 240V from the house) and the main capacitor (I think it's a capacitor) melts / explodes at the spade connector (it's a thick blue wire). Just so it's clear, this is a wire that comes in the unit from the factory, not the incoming 240V power that's added and used to supply electricity. Last time, I just replaced the spade connector and it was working until now but has failed again a few days ago.
Has anyone experienced this? Should I maybe replace the wire with a heavier gauge one? (Can't do much with the spade connector since it's it's on the relay and on the capacitor). Any other suggestions?

The location.jpg picture shows you where they connect to the relay (both attach behind the red wire (which is the incoming power)) and the one that melts goes down to the top left of the capacitor. The wire.jpg picture shows the wire and the sheilding basically melted and stuck to the wire that's next to it.

Let us know. Thanks, Mike

 

[JamesW]

Pictures?

 

[JoyfulNoise]

I would have an HVAC tech come and look at it. A heat pump is essentially equivalent to the compressor side of an AC unit and that start/run capacitor has to be rated for the system. Sounds like either the capacitor is bad or there’s something wrong with the compressor drawing too much current

 

[micheldb]

Pictures?

after I posted I thought of that so added 2 pics.
Thanks

 

[JoyfulNoise]

If you have a digital volt meter with capacitance and resistance testing, you can easily check the capacitor. My guess is the capacitor is shunting current to ground and that over current is causing the wire to overheat. What’s worrisome is that your breaker isn’t tripping to protect the equipment.

 

[JamesW]

Definitely something odd going on.

Can you show pictures of the whole wiring compartment?

Maybe get a thermal camera to check the electrical components after everything is fixed to see if anything is getting too hot.

Check the voltage and current to make sure that they are in the correct range.

 

[ajw22]

Have you reported the problem to Raypak?

I would confirm with Raypak that the correct specification capacitor was installed.

I would replace the capacitor with a new one of the same specifications.

I would talk with an HVAC tech about installing a Soft Start Kit that should moderate the starting current.

 

[micheldb]

Thank you very much for all the suggestions. If nothing else, you've made it clear that I'm in over my head and need to hire an expert !!!

FWIW, it's wired with the recommended minimum breaker (50A) and the breaker has never tripped. We've been using it for about 3 years now and it was never an issue with it until the connector blew up last year. We bought it used and the previous owner used it about 3-4 years before us. (He didn't mention any issues and I don't remember seeing "burn marks" on the case near the relay which are pretty obvious now so I suspect they never had an issue).

 

[ajw22]

Given the age of the HP I would replace the capacitor.

Wire melts like that from cumulative overheating over a long period of time. That wire has been running hot for a while and slowly melting the insulation.

After you get it running again you should periodically open it up and check on the condition of the wire.

 

[JoyfulNoise]

Also, that contactor looks like it has corroded connections. In any heat pump electrical system, the contactor and capacitor are considered serviceable and consumable components. When the unit switches on and off, that contactor has to handle a huge in-rush current and does so with every on/off cycle. Contactors don’t last forever and I know on my outdoor AC units that I have changed then out regularly every few years. The start/run capacitor is the same way - it handles large currents at start up and needs to be checked annually. They either fail catastrophically (swell and “blow up”) or less noticeably through higher and higher leakage current. Any HVAC tech knows how to test them while the system is running and there’s online videos about how to use a standard volt meter with current clamp to measure capacitance. Once a cap is 10% out of spec, they are considered bad and should be replaced.

 

[JamesW]

A hard start kit might be helpful if the compressor is not turning over easily.

However, if the compressor is not turning easily, it will probably need to be replaced at some point.

Most likely, you would just replace the whole unit instead of just the compressor.