Heat pump question

This is an issue on my son’s 20 month old heat pump. So what do you all think before I go off and spend big bucks.

2.5 ton Lennox. R-410A

During winter, the compressor would shut down after 2 minutes. First it was a high limit issue, then it was a low limit issue. No leaks. Levels fine. After trying a couple more times, the compressor starts making a strange growling noise after 30 seconds and shuts down.

Installing company tech says compressor is shot. Have to replace. Compressor is covered by warranty but labor (their quote $1500) is not.

Decided to wait until now to have it worked on. So just for S hits and Giggles I reset it one more time since it is 88 degrees out. Unit turns on and runs great. No noises at all. Has kept the house at 71 degrees for 4 days now in 95+ heat and is running smooth.

So before I jump and pay the money to change the compressor, any other ideas out there? Reversing valve? TXV? Anything that might be done without evacuating the system which is where the cost is?

Thanks all.

How long are the refrigerant lines? Are they old lines from a previous system? Does it havwe a liquid line filter/drier installed? If longer than 50 ft or vertical rise over 20ft a kit should have been installed to prevent “slugging” or something like that. Some manuals state 10ft vertical rise but their engineer told me it should have said 20. The “growling” you mentioned sounds like what an engineer at Bryant told me about, he said it would sound like gravel in the compressor if something was wrong with the refrigerant flow but I can’t remember exactly what issue we were discussing then.

These R410 units will shut off the compressor at times (not defrost mode) to control head pressure in low load conditions during heating mode. I thought mine had problems after a major power outage which resulted in finding out none of the installers or techs knew squat about these in 2002 so I pulled some tricks to get an engineer on the phone. We talked for about an hour about R410 heatpumps.

New lines at install. Filter / Drier installed. Level run of about 40 feet with a 4 foot drop at the inside unit. (basement install)

1500 labor to change out a compressor? Wow!

Sounds like the reversing valve got stuck half way or the control voltage acted up during a reverse such as defrost mode.

Make sure it has a bi-directional filter/drier and not just a one way type.

I will be in Washington in a couple of weeks, do you want me to look at it? :slight_smile:

A grumbling noise at start up is liquid refrigeration or oil on the compressor. Something is amiss in heating mode.
This is way over the head of anyone here because we can see anything from here.

In a situation such as this, I would have a very difficult time and relying on the work force out there!
This is not a common situation and probably less than 1% know how to deal with it.

High limit trip can be from oil restriction. Low limit trip can be oil restriction.

When Lennox out with their first scroll compressor they refused to install accumulators (trying to save some money).they also refused to allow aftermarket start capacitors with potential relay kits.

At any rate, you’re getting oil/liquid refrigerant migration for one reason or another back to the compressor.
Why this is happening, I can’t tell from here.

In the summertime things will work just fine because the refrigerant will not condense to a liquid on high temperature ambient temperatures.

I was wondering when you were coming back out west. Let me know when you are in town. Lot’s of tricks out here. Restaurants and rental cars are cheaper away from the airport. We like tourists to pay for our professional sports stadiums you know.

It would be great if you could take a look but I sure dont want to slow down any plans you might have.

I don’t plan on doing anything with it during the summer. The compressor is just humming along without a care in the world.

Give me a call when you get close to arriving. I look forward to finally meeting you.


Steve , I plan to fly into San Francisco and drive up US 1.

Since my last visit my daughter moved to Seattle.

As my itinerary gets solidified, I will let you know if I’m in the AO! :slight_smile: