Possible restriction or bad compressor

[akelesis]

i was kinda out of line with my earlier reply, sorry to otto i was just thinking out loud. im just a tech that just got into the trade a few yrs back and i am totally interested in this call its a good one to see.

call me a newbie i can accept that (-:
what i learned from watching my senior tech was to eliminate things to the system. i dont like it that the head is only at 120 psi (whats the actual temp on the suction line with your gauges) which is odd that number should be a lot higher for sure. any restriction anywhere in the line would cause frost build up check for that too (pressure drop causing frosting)

before you do anything else make sure the amps on the common side of the compressor is where it should be compared to the rated amps on the name plate to ensure its not low on charge. if this compressor feeds 2 evaps then make sure both systems are calling get superheat reading. ( is it possibe for the compressor not pumping correctly> valves leaking over to the discharge not allowing head to rise?)

if its the head master control that is the problem you will know right away by having the clamp on thermometers and seeing the temp difference from inlet and outlet(s) but it doesnt seem to be the problem --do process of elimination is key-- hope i was informative and not being a pest (-: i really want to see the outcome on this one thanks all for having me think out loud

good luck Otto

[jpsmith1cm]

lot higher for sure. any restriction anywhere in the line would cause frost build up check for that too (pressure drop causing frosting)

This is inaccurate information. Only a very large pressure drop will cause frosting on the liquid line. Only by measuring pressure can you accurately determine if there is a pressure drop.

before you do anything else make sure the amps on the common side of the compressor is where it should be compared to the rated amps on the name plate to ensure its not low on charge.
No common on a 3 phase compressor.


if this compressor feeds 2 evaps then make sure both systems are calling get superheat reading.

Good advice.

( is it possibe for the compressor not pumping correctly> valves leaking over to the discharge not allowing head to rise?)

Yes, but your suction pressure would be much higher.

if its the head master control that is the problem you will know right away by having the clamp on thermometers and seeing the temp difference from inlet and outlet(s) but it doesnt seem to be the problem --do process of elimination is key-- hope i was informative and not being a pest (-: i really want to see the outcome on this one thanks all for having me think out loud

good luck Otto

I agree on the headmaster. Typically they raise the pressure when they fail.

[otto8]

Thank you for your support guys.... What about them txv screens or txv? Should I replace them because they have black color on them.... Reciver? Have you guys had every clogged condensor?...

[jpsmith1cm]

screens get cleaned and reinstalled. no need to replace them.

by clogged condenser, do you mean plugged internally? I'd have a very hard time believing that one.

[Snapperhead]

Take your torch and run it up and down the receiver and then run your hand from bottom up until you find hot spot. Hot will indicate liquid level.in receiver. May take a few tries at first. A good diagnosis tool.

Whats a good level to have ?

[jpsmith1cm]

Whats a good level to have ?

with a headmaster, it's hard to say. It will depend on ambient conditions.

You must maintain a liquid seal in the receiver at all times.

[SandShark]

Since the system has a head pressure control valve (LAC?), can I ask you what the ambient temperature was at the time you were working on the system?

[mizzterclean]

Make sure all fans are running and torch receiver. I would say approx 40-50% level. Always make sure you can pumpdown and pressure controls set accordingly. Remember not all compressors equal so ci/co will vary.

[2sac]

Nameplate says R22 but what about the powerhead on the txv? To check for a restriction inside the condenser you will need to check pressures on the discharge and liquid lines. (I have only seen this occur once in 14 years) What pressure is the headmaster rated at? Is it possible someone installed an R12 headmaster or a dual pressure headmaster and you are charging based on the sight glass but the system is undercharged because of the incorrect headmaster?

[TheBeastFromTheEast]

Just a rule of thumb. When you have a receiver on a system you never want to charge the system by checking the sight glass for bubbles.

[jpsmith1cm]

Just a rule of thumb. When you have a receiver on a system you never want to charge the system by checking the sight glass for bubbles.

This is completely incorrect.

You MUST maintain a liquid seal in the receiver AT ALL TIMES!


If you do not have a liquid seal, then you are undercharged.

http://www.sporlanonline.com/90-30-1.htm

Please stop such disinformation.

[zuke19]

you sound like you almost have the same problem as I except my discharge is ok-1st of all I don't believe you have a restriction, the head pressure should be higher, if you want to verify, shut the compressor off and see how fast it equalizes, make sure solenoid is open, on a 3 phase system there is no common, check the voltage at the compressor to make sure it is not low, you stated that the condenser was blowing off cold, the receiver was hot, you might have a headmaster on it, how cold was it outside? The condenser needs to have a split, is the condenser outside or on the roof of the cooler? it will not have a split if the headmaster is bypassing it, the headmaster will control it to 180 psi

[zuke19]

also the system worked fine for years before you, so now if no one worked on it, something else happened, so most likely the headmaster and txvs are right, so ask yourself what could have changed during this time if no one worked on it, and you will find the problem faster that way