We know its baffling to you. That's why you're here. Trust us. We know
what we are talking about. Now go get a new thermostat. You might want
to also install one of those new ReverseFlow@ductboosters while you're
Clack? Oh shit! Never mind. You need to replace your system
He was actually giving away a possible cause of the problem. What sometimes
happens is that the stat starts the compressor - that's the "one solid
clack" you hear. Now, the system comes up to normal operating pressure. The
thermostat might have a problem (it might not even be the stat's fault -
think door slamming near a mercury stat) where it momentarily allows the
contactor for the compressor to open. Now it closes the contactor again.
We've got head pressure, so you wind up with a locked rotor condition. If
the compressor is running, it draws - oh... something less than the rating
of the breaker feeding it. During a start, and while you are in a locked
rotor condition, it sits there drawing whatever it feels like - some large
multiple of the recommended breaker rating until something gives. That would
be one of the thermals, the breaker feeding it, or the wiring to it, or the
windings. Something is wrong with this picture. It could very well be the
thermostat. The real expensive, good ones are recommended for a good
reason - they generally have a parameter that allows the knowledgable
installer to control the minimum cycle time.
From what you've said, it's been happening every six months for the past 12
years. That means - to me, anyway - that six months after you had this unit
installed, it burned it's first set of leads off. After the second time it
happened - and certainly during the 7th, 8th, or 9th year it happened - you
should have been asking a few questions about why it keeps happening, and
what they plan on doing when the manufacturer's / installer's warranty is
over. The wire to that you are trying so hard to re-attach is so badly
corroded, and contaminated with Hydrochloric acid from the burned PVC that
there is no hope of a permanent repair with the present wire. You need to
find someone who knows what they are doing to look at the unit, and assess
whether the terminals are too far gone, whether there's an issue with the
control system, and whether it's just time to say goodbye to it. That would
likely be someone other than who's been out there between 12 and 24 times
for the "same" problem.
Somewhere along the line, did they at least suggest replacing the
compressor, and you didn't want to pay the labor? When you are messing with
those terminals, are you using correct PPE? Remember that there's 50-100
PSI - when it has been off for a while - behind those innocent looking
little studs. The glass seals have likely been stressed by the heat, and a
nice R-22 / oil injection into your hand might be the most minor thing that
could happen. BTW, you could lose fingers / hand later due to gangrene if it
lets go, and the conditions are right.
This thermostat cost $125 12 years ago. It uses a thermistor not a
mercury switch. It has a cut-out timer in it such that if the signal
to the a/c unit is lost for any reason there is a 4 minute delay
before it will call for cooling again. Also, there is a similar,
redundant, cut-out timer in the condenser unit that won't let the
compressor start again after a power dropout for about 3 minutes. I
never see this one in action because the delay in the thermostat is
This lead is the Term-Loc lead that was installed about 6 weeks ago.
They only burn back about 3-4 inches from the compressor terminals. I
cut this off when I redo them.
Udarrell have gave you good explanation I had
few of those myself but so far none repeated, these is what I do
when you replacing terminal (stay-cons) first make sure you wires
are rated for current require, crimping wire some time it is not enough
you may need to solder in and then make sure that terminal fits on tight
you can also squeeze in terminal part that goes on to log before it is
pushed on, after that is complete you can add small glob of silicon
compound on to each terminal preventing getting moisture on
and helping keep rust off.
Good luck from Dido
IF the super boost was correctly installed, it *might* help, so would
correctly wiring that replacement run capacitor(it *IS* the correct value,
isn't it?)...however, the contactor looks like it has been arced across and
it should probably be replaced and the original problem corrected. Unless I
miss my guess, its a Goodman unit that has been repeatedly hacked over by
the lowest bidder and then screwed with by the owner.
Its pointless to ask what kind of metering device does the system have??
When the compressor *IS* running, what is the SST and superheat?? What is
the LLP and subcooling?? What is the amp draw on the compressor??
Best you can hope for is to call a *competent*(not cheapest), licensed,
insured, professionally trained, HVAC technician to come straighten out your
It's a Copeland compressor in an Amana condenser unit.
The "hacking" I've done is:
changed the contactor once
installing inadequate connectors (same as the original installer used)
when they burned off
shortly thereafter installing the Term-Loc wires -- at your suggestion
if I recall correctly
installing the inadequate connectors twice more in the last couple of
weeks after the Term-Loc wire burned off.
The last two events prompting me to post this question.
This depends on the conditions. The last time I made measurements
these were the conditions and results:
indoor temp 74
outdoor temp 95
saturation temp 38
suction line temp 45
superheat should be 7 per manufacture's pamphlet
18 amps -- about right for the conditions per manufacturer's pamphlet
Part of your problem is that the system is overcharged and the compressor is
sweating and most probably causing the terminals to be wet all the time
causing high resistance connections.
With a 67 PSI SP, I would look for an SST of approximately 58 degrees with a
fixed oriface(piston) metering device. Recover the refrigerant overcharge,
and try again.
Noonair made some good observations, do not flat out tell him he is
wrong! If the compressor is sweating too much it can create problems
with the terminals.
Superheat does not mean anything if the airflow is too low or there is
an insufficient heatload going through the evaporator coil.
It could be overcharged, -read the linked page!
I have not read all the posts so don't have enough info to make any
meaningful assessments! - udarrell
Air Conditioning\'s Affordable Path to the "Human Comfort Zone Goal"
I said he was wrong about the superheat of 7 not being correct. In
effect I said he was wrong in saying *I* was wrong about the
superheat. Maybe you want to tell me how I misread the superheat
chart I linked to.
I didn't say he was wrong about that.
I don't disagree with that. Some *other* problem making the factory
specified superheat meaningless was not the issue. Other problems can
cause all kinds of difficulties. The issue was whether the superheat
I quoted is what the manufacturer specified, and it is.
Thanks for the link. It seems to deal with systems that are
performing below rated capacity. I don't have that complaint.
I've read all this back and forth and can't really answer your
question... except to give you another avenue to look at...
I'm an electrician and NOT a HVAC guy, so take it for what it's worth.
What you describe are classic symptoms of a low voltage condition on
Look at the side of your condensing unit and see what the required
current is.... and then compare it to the wire size you have going out
Check all of the connections from the breaker, to the disco, to the
unit. Clean and re-tighten all of them (with the breaker off, of
course). Open/close the disconnect.. and while open inspect the thing.
Does your home have a adequate (in these days meaning at least 200 amp)
Did the contractor make the aluminum/copper wire transitions correctly
Starting current is one heck of a lot than what it takes to run the
thing... and I'd surmise that's where the problem is... a low voltage
condition on start due to bad feed capacity or poor connections somewhere.
Just my 2 cents worth.
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