Thanks for the help. I have a Lennox HP25-411-1P that is paired with a
Lennox CB19-31-2P inside unit. I have been having problems with the
compressor shutting off with a thermal shutdown. It is extremely
erratic. Sometimes it will shutdown and sometimes it will not. When
the tech was here it did shutdown. The tech who looked at it said
compressor current draw is normal. However, he said the charge looked
low. Said that when R22 was added, head pressure went up, but suction
did not. He said that he found that there was only a 10 degree temp
differential across the evaporator coil. Said the temp on suction was
64 degrees and that the TXV is bad and is not allowing enough coolant
back to the compressor to help cool it. Price to fix $1100. This seems
really expensive to me since the part is only about $160. They are
charging $36 a pound for R22 and since the system takes 10.5 pounds
that adds up quick. The unit is 12 years old and naturally since they
sell units they say best course is a full replacement of the heat
pump. Should I be looking at another service tech for their opinion?
Is this price high to replace a TXV (drier also by the way)? I'd like
to go with a geothermal when I replace this, but could not swing it
today, so if the TXV replacement was only going to be about half of
the quote, I'd go for it. It would be nice to get a few more years out
of this heat pump.
On Fri, 29 Jun 2007 11:33:06 -0700, email@example.com wrote:
Price is relative to where you live and what company you get. That
price may be high in one area and low in another. Refrigerant is going
up by the month. Nothing is cheap including labor. Look at the price
of gasoline. I dont like that one bit but thats the way it is.
Anyways, if you are concerned with the price, get another estimate or
two. Your conversation on the phone to another prospect company might
include your current system problems, the course of action your
current company has chosen and maybe asking for one of their more
experienced service techs. Armed with that info, you might be suprised
at what you find out.
By the way, 10 lbs aint diddly. I have a 2.5 ton 14 SEER heat pump
that holds about 20 lbs!!
Remember A/C is a luxury, not a necessity.
First, the R-22 can be pumped down into the condenser & sealed off using
the service valves; there is no reason to get rid of the R-22 unless it
He may possibly be charging you for R-22 when there may be little or no
need for it
Additionally, there may be NO legitimate reason to replace the TXV,
proper troubleshooting is required to establish if it is bad.
Can he show you the tests 'that prove' the TXV is bad?
Second, many TXVs are adjustable as to how low you want the Superheat to
be. Also, he sensor bulb should be removed and emery paper used to make
better contact & heat transfer to the bulb; the bulb also needs to be
mounted in the proper location on the line.
Third, the TXV keeps the refrigerant flow rate constant to maintain a
specific Superheat setting, adding refrigerant is not likely to change
the suction; a change in the heatload through the evaporator will change
the R-22 flow rate toward maintaining that Superheat setting.
Fourth, the TXV may not be the sole cause of the overheated compressor.
Is the condenser coils & fins clean & the motor delivering its full RPM,
if it's a PSC motor check its run capacitor!
http://www.udarrell.com/ac-trouble-shooting-chart.html - udarrell
If you allow them to replace the TXV that may not solve the problem.
Check the temperature of the air leaving the condenser as compared to
the outdoor temp & post those temps & the split in degrees-F.
Perhaps the 10-F split across the evaporator is due to a non conditioned
source of hot air being drawn into the E-Coil just before the air enters
Are you located in a high humid climate? If the compressor is getting
hot I would quit running the AC until the cause(s) of the problem are
located & fixed!
WISDOM PRINCIPLE DIRECTED EMPOWERMENT COMMUNICATIONS -
THE REAL POLITICAL ISSUES and WISDOM BASED PEOPLE EMPOWERMENT
So how does one go about finding a reputable HVAC person to tell me
what is wrong? I gave you all the information that the tech gave me.
With that is how he said the TXV was bad. So I guess you are saying he
did not know what he was doing? I live northwest of Philadephia. Know
any good HVAC techs here? Today it is humid and about 75 degrees
outside. The temperature of the air leaving the evaporator is 52
degrees. So that is a 23 degree split. The compressor will run an
hour today before it shuts down. Yesterday, at the peak of the heat
(95 degrees) it would run about 10 minutes. To be honest, it does keep
the house at a constant temperature. I only noticed this because I
turn the temp up in the morning and lower it at night. I was noticing
that sometimes it took too long for the outside unit to start. This
copeland compressor has a replaceable temp limit on it. I thought the
sensor could be bad but since it supposedly triggers at 280 degrees
have no way to test it. Tech said that was not bad (he did not do any
testing to it - just said that). He did put a thermometer on the
compressor by the sensor but it never went above 150 degrees (note
that the sensor goes into the case though).
So my guess is I need a good tech and do not know how to find one.
Naturally everyone will charge me a couple hundred dollars to tell me
what is wrong. I do not have a problem with that, but want it to be
I am Refrigeration Tech. and not AC person however unless
unit is running with low back pressure 9-1 there is nothing
wrong with TXV must likely low on charge (gas) or perhaps
compressor loosing compression (not pumping) get some one
ales to look at your unit because one that you had seems
to be big scammer.
FWIW- I think I have only changed one of those temp sensors on Copeland
scrolls. It goes down into a well that is definitely more than an inch.
As I recall it is somewhere around 4 inches. Years ago our local Rheem
distributor did not stock them-- said they were not needed and to bypass
them. I have no idea if that came directly from Rheem, or just the dist.
I never bypassed one though. Actually the one I replaced was on a
Lennox, but I got the part from the Ruud dist. One thing is for sure--
they are right proud of them-- $$$$$. With the sensor going down into
that well, I would guess that it is sensing winding temp as well as
discharge. I would make sure the run cap is at its rating, and that all
the electrical connections as well as the contactor are good so the
compressor is not running hotter due to low voltage.
On Jul 1, 1:20 pm, firstname.lastname@example.org (lp13-30) wrote:
The Lennox service manual does specifically say discharge temperature
is what is being sensed.I can feel that top of the sensor, so it can't
that far down there. I think reading discharge temperature is a
reasonable method. If it shuts down and the discharge temperature on
the pipe is up in the 200's, I'd be suspicious. I got an online quote
for $120, so yes it is not cheap. The contacter does look a little
charred on the contacts so that is interesting. I can check to see if
there is a voltage drop across it. How does one check the run cap?
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