On May 10, 3:02 am, Jason wrote:

Based on the symptoms I posted, does a faulty reversing valve seem
like a reasonable diagnosis? I can save myself $100+ if I call the
repair guys and just tell them that I need a quote on replacing this
specific part, instead of having them come out to look at it
themselves.

First let me preface my comments by saying that you may not want to
take your air conditioning advice from a guy who writes software for a
living (although I do have a degree in electrical engineering).

I assume that the checking up to this point has included proper freon
levels.

20 years ago, had a problem with a Goettl (big brand here in AZ) heat
pump on my roof. As others have said, in a heat pump, there is a
reversing valve that basically reverses the direction of flow of the
freon, so in winter you're removing heat from the outdoors and
bringing it inside.

My problem was that when we got to winter and wanted to heat the
house, we turned the thermostat to Heat, set the temperature, and
things just got colder - the heat pump was stuck in cooling mode, so
it was never going to reach the set temperature. Sounds kinda like
your symptoms.

In my Goettl, the reversing valve was actuated by the house line
voltage. Since thermostats do not switch line voltage directly (they
operate on 24 VAC sent down to the thermostat from a transformer in
the unit), there is a relay in the unit that is supposed to switch the
reversing valve when you change the thermostat from cool to heat. In
my case, the relay that controlled the reversing valve was sticking,
not switching line voltage to the reversing valve. A good whack with
the butt end of a screwdriver was enough to unstick the relay.
Replaced the relay anyway on the theory that it would probably stick
again. Cost - a couple hours of my time and about $20 for the relay.

My point is that it may not be something that has to touch the freon
loop, where things start to get expensive. A simple check with an AC
voltmeter will tell whether line voltage is getting to the reversing
valve or not. Now if you have voltage to the reversing valve and it
still is not working, then the reversing valve may be bad and you're
going to end up opening up the freon loop to replace it - that is work
that is definitely best left to a pro. Like others have said, the EPA
wants you to recover the old freon instead of venting it to the
atmosphere, then you gotta pump the system down before putting in new
freon. And freon is pretty pricey these days, I think AC guys in
Phoenix are charging around $100 a pound, I remember when you could
walk into Pep Boys and buy a 1 pound can of freon for your car for
about $5. But, if you know what you're doing around electricity, can
read a simple schematic, and have access to an AC voltmeter, a little
detective work can point you in the right direction.


Hope this helps,
Jerry