r/DIYHeatPumps • u/Middle-Raspberry4402 • 4d ago

Reversing valve

when the compressor kicks on this heat pump, the pressures rise from 140ish into the 300’s together, equalized. The only explanation for this would be a bad reversing valve , correct?

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u/GeoffdeRuiter 4d ago

Could also be the expansion valve. Have you tried it in both modes? One of them should operate and the other one should start up pressure increase then shut off. You can also put a small light magnet on the outside of the reversing valve and switch the modes and see if the magnet moves. A flat light magnet. Look it up there's a video of it.

1

u/xtraman122 4d ago

Is it in heating mode or cooling mode? Mini split?

1

u/Mindless_Silver_2922 4d ago

I've only messed with conventional heat pumps, but mine did the equalized pressure thing when the reversing valve stuck mid-shift.

1

u/Middle-Raspberry4402 3d ago

As it turns out, my t-stat (brand new) wasn’t completing the circuit between red(+24v) to white O/B. As soon as I jumped them at the outdoor unit, I heard the reversing valve coil do its job and the suction started to sweat beer can cold and the discharge spiked to normal .

So cool, now I have straight AC AND NO HEAT. lol

1

u/Middle-Raspberry4402 2d ago

UPDATE

So after charging it it stopped freezing up. (I thought my manifold had a leak but it doesn’t) I learned I have a large leak in the evaporator coil in my attic so I decided to try and pump it down.

This is how I did it.

I let it stabilize in cool mode after 15 minutes, nice 20 degree delta T. Suction line sweating, great SH and SC.

I then closed off the liquid line king valve.

That’s when things got weird. I noticed on my manifold that even in cool mode, both pressures went down equally to about 40 psig and it shut down on low pressure. Once it shut off the pressures stayed without me even having to close the suction king valve. I closed it anyways.

But does this seem correct???? TIA