6-week old Ducane blowing hot air

My husband and I had a 14-seer Ducane installed 6 weeks ago and it is blowing only hot air now. This started yesterday. Tech came out yesterday and can’t figure out what is going on, he has two theories, 1) the suction valve is too small (have a 5/8", he says it needs a 7/8") or 2) the expansion valve is bad.

He called the mfg. this morning and they said to turn off the unit for 2 hours and then turn it back on as this would allow the suction valve to do whatever it does to get back to normal. Well, that didn’t work. It is over 100 degrees outside and 88 degrees in the house…I’m dying!

The tech is stumped, he is coming back over soon and I would love to help give him some suggestions…has anyone seen this before? If so, what did you do? Any other ideas I could give the tech?

Thank you in advance!

Shannon; it is impossible to troubleshoot over the internet. I would have to see the suction and head pressure on my gages. Valves are not determined in fractional inches. The size of the liquid and suction lines are determined in inches or fractional inches; the length of the line set is also a determining factor. If the suction valves have gone south it is very easy to determine this by simply closing the liquid line valve and watch the suction pressure on the gages as this pressure should go to a negative if the valves within the compressor are operating properly. Your service tech should have already performed this task.

You mentioned expansion valve; there are different types of metering devices
and I don’t know what your system has installed; but yes if it is a true expansion valve they can cause the system to not cool; this also is very easy to deternine by simply forcing the expansion valve plunger to the full open position and I have used a dime under the power element to force it open and provide temporary cooling until a replacement could be obtained.

I could go on and on about this but it sounds like you need a old dog to get your unit running properly. Good luck your service tech needs to have gray hair:D
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What did you upgrade from. A lot of the time the lines need to be replaced with larger lines. We had a case not too long ago where they used the old lines and due to the pressure tiny leaks developed in the lines under the home. Once they installed the right lines (up and through the attic) all was fine.

If the unit worked property for the first 6 weeks, it is very unlikely that the line sizes are too small as they were ok until yesterday. It is more likely that you have an ‘infant failure’ of some other component. If the service tech can’t find it quickly, insist that he call his are service support organization.

Agree with Frank. We installed a Payne on my own home some years ago. I changed everything including the line set for precisely the reasons above and due to the fact the original equipment must have been installed by monkeys who did not do anything right. The new Payne AC unit worked for 5 days and stopped abruptly. The trouble could be traced to the compressor which was replaced and the broken one sent back to the factory. The report came back stating the compressor had been wired backwards at the factory. Didn’t know it would even run like that but that is their story and they are sticking to it. Things can come from the manufacturer in a faulty condition.

Run the unit and look for frost. This indicates the location of a restriction.

If you had a failure from the past unit, it may be clogging filters, dryers, screens.

What are the refrigerant pressures?

What is the temperature of the suction and liquid lines?