Is New Compressor Needed?

[scouts22]

Symptom: Had an 80* OAT day and turned on AC. 83* inside. Inside set at 77*. While vent air seemed reasonably cool, took 1-3 hours to drop to 80* inside. Hours later, dropped to 79* inside.

Current HVAC:

Gas Furnace: 92.2 AFUE York/Unitary P3URC14N09501D
Coil: York/Unitary G1UA036S21C R22 or R410A option but don't know which is being used
Compressor: Goodman CKJ30-1A

Don't know furnace/coil age but booklets for furnace/coil are copyright 1999-2000. Service guy says compressor is from 2000, but I did not see on label (I wasn't present for service call).

Service guy told wife 2-ton compressor worn out from age. $$$$ to replace but no specifics on brand/model.

Question-do I need a new compressor? If so, do I replace compressor or start with a new system from scratch (say a heat pump). Thank you for any help.

[jpsmith1cm]

I'd be looking for a second opinion.

a. If it's cooling at all, the compressor is probably fine.

b. A 12 year old compressor isn't "worn out from age"

[mark beiser]

b. A 12 year old compressor isn't "worn out from age"

This!

If a 12 year old compressor is dead, it wasn't old age, it was murder.

[scouts22]

Today, I talked with the service guy. He said the low pressure is 52 and the high is 68, indicating bad valves and necessitating replacement of the compressor. Although he charged me for a full routine AC service, he said he never looked at the inside unit other than to check the filter.

He had also suggested to my wife yesterday that replacing the whole sytem makes more sense than just replacing the compressor. I'm not sure how he came up with that recommendation if he didn't look at inside system (furnace/fan/coil).

[wahoo]

This is a 2 1/2 ton unmatched system. At 12 years of age, I'd not recommend replacing the compressor. Replace the entire system with a matched system (inside and outside units).

[udarrell]

Symptom: Had an 80* OAT day and turned on AC. 83* inside. Inside set at 77*. While vent air seemed reasonably cool, took 1-3 hours to drop to 80* inside. Hours later, dropped to 79* inside.

Current HVAC:

Gas Furnace: 92.2 AFUE York/Unitary P3URC14N09501D
Coil: York/Unitary G1UA036S21C R22 or R410A option but don't know which is being used
Compressor: Goodman CKJ30-1A [12-SEER 2.5-ton +1998-2000, think it's R-22]

Don't know furnace/coil age but booklets for furnace/coil are copyright 1999-2000. Service guy says compressor is from 2000, but I did not see on label (I wasn't present for service call).

Service guy told wife 2-ton compressor worn out from age. $$$$ to replace but no specifics on brand/model.

Question-do I need a new compressor? If so, do I replace compressor or start with a new system from scratch (say a heat pump). Thank you for any help.

scouts22;Today, I talked with the service guy. He said the low pressure is 52 and the high is 68, indicating bad valves and necessitating replacement of the compressor. Although he charged me for a full routine AC service, he said he never looked at the inside unit other than to check the filter.

He had also suggested to my wife yesterday that replacing the whole system makes more sense than just replacing the compressor. I'm not sure how he came up with that recommendation if he didn't look at inside system (furnace/fan/coil).

With bad valves normally the low side is not a low 52-psig pressure, but a high low side pressure; with bad compressor valves the high-side head pressure drops & the suction pressure rises way above normal. That reported scenario sounds fishy to me...may just be wanting an equipment change-out...?

Small chance, but perhaps the valve core was not depressed enough to get an accurate high-side reading; but I question what took place by the service guy.

If the pressures were as he indicated there would be no cooling. What is the temperature of the air coming off the condenser as compared to the outdoor temp; list both temps.

What is the temps of supply air & return air in your home?
There are other indications that don't make sense with what you were told...

There are other diagnostic checks that a PRO could use. A blocked filter-drier inside the condenser could cause a very low high-side reading at the liquid high-side port as the liquid refrigerant merely builds up in the condenser; a condenser can hold all of the liquid refrigerant in the system.

By all means find another contractor for a more comprehensive diagnosis & opinion; don't tell them what the other guy said.

[scouts22]

udarrell: "If the pressures were as he indicated there would be no cooling."

jpsmith1cm: "If it's cooling at all, the compressor is probably fine."

The service guy did mention when I called him today that he was "surprised" I was getting some cooling. Guess that means he realizes there may be a flaw in his diagnosis but he didn't follow up on it.

BTW, I can't figure out how to make the multi-quote thing work here. I'm maxed out at one quote. Thanks.

[udarrell]

udarrell: "If the pressures were as he indicated there would be no cooling."

jpsmith1cm: "If it's cooling at all, the compressor is probably fine."

The service guy did mention when I called him today that he was "surprised" I was getting some cooling. Guess that means he realizes there may be a flaw in his diagnosis but he didn't follow up on it.

BTW, I can't figure out how to make the multi-quote thing work here. I'm maxed out at one quote. Thanks.

Well, there could be some cooling with a partially plugged liquid line filter-drier inside the condenser; depends on the extent it's plugged.

Depending on outdoor dew point, frost should be indicated on filter-drier & down-stream from it, if no frost due to very low dew point temp,the drier & down-stream tubing should be a lot colder than up-stream toward condenser coil.

The pressures indicate is NOT bad valves.

A clogged liquid line filter-drier inside the condenser is the most likely cause of a pull-down on the liquid line pressure port; it would turn the liquid line into a virtual suction line pull down condition.

If the liquid line service valve were nearly closed by someone servicing the system the same condition would occur.(?)

Let's hope that didn't happen...

Sorry to be so negatively speculative... but the signals are there...
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Hi-lite the other post you want to quote & paste it below the original Quote, then hi-lite it again & click on the Quote tab, 4th from the right, - that will also Quote it.

[jpsmith1cm]

Today, I talked with the service guy. He said the low pressure is 52 and the high is 68, indicating bad valves and necessitating replacement of the compressor. Although he charged me for a full routine AC service, he said he never looked at the inside unit other than to check the filter.

He had also suggested to my wife yesterday that replacing the whole sytem makes more sense than just replacing the compressor. I'm not sure how he came up with that recommendation if he didn't look at inside system (furnace/fan/coil).

I do not accept this diagnosis.

I would expect MUCH different pressures from a failed compressor.

If you've got the cash, a new system is a good way to go, but I'll bet that this one can be repaired for less money.

Have a look at our Contractor Locator Map and see if there is a contractor near you.

[jpsmith1cm]

udarrell: "If the pressures were as he indicated there would be no cooling."

jpsmith1cm: "If it's cooling at all, the compressor is probably fine."

The service guy did mention when I called him today that he was "surprised" I was getting some cooling. Guess that means he realizes there may be a flaw in his diagnosis but he didn't follow up on it.

BTW, I can't figure out how to make the multi-quote thing work here. I'm maxed out at one quote. Thanks.

This scares me a little.

IF you don't have faith in your tech, then you need to replace him, not a compressor that is still doing it's job.

[Mr Bill]

I do not accept this diagnosis.
I would expect MUCH different pressures from a failed compressor.

Those pressures don't indicate any bad valves to me, something is wrong if it has those pressures, but bad valves?

[udarrell]

Depending on outdoor dew point, frost should be indicated on filter-drier & down-stream from it, if no frost due to very low dew point temp,the drier & down-stream tubing should be a lot colder than up-stream toward condenser coil. [That was an incorrect statement by me!]

My quoted post above needs some clarification.

Dew point is relevant to when a suction line sweats or not.
It's not relevant to when a line gets below the freezing point.

Let' take an R-22 TXV metered evaporator set for 12-F superheat.

First load is very light & you read only 62-psig suction that's only 35-F Saturated Suction Temp (SST), add 12-F Superheat & the line temp is 47-F, usually the dew point is going to be well above that temp. That is even above beer-can cold.

Second load is an 85-psig with a 51-SST add 12-F SH 63-SLT.
The dew point could be below that temp & therefore NO sweating on the line; also a 63-F suction line is not going to feel beer-can cold.

We have to take both the suction & high-side refrigerant line temps & pressures & do the math to get both Superheat & Subcooling so we know what we're doing; beer-can cold & a sweating line does not work, it's even more critically important on high SEER systems that operate at higher suction pressures & line temps, with a given heatload....

[TwincamDave]

Sounds like you need a more qualified tech to check this out.