410a heat pump trouble shooting

[ttbone72]

Hello all,
I was at my mother in-laws yesterday when i felt cool air blowing on me i went out to heat pump and felt suction line it was out door temp so I pulled disconnect,went home and got some tools. it was about an hour later pushed in disconnect with amp meter and gauges hooked up compressor fired right up pulling 7.75 amps 118 suction and 320 head pressure for about 12 min; I was just getting ready to load my tools up when the unit started straining the suction pressure stayed the same but the head pressure started climbing. The head pressure was at 575 when I energized the reversing valve for a few min. then swithed back to heat it again ran for about 10 to 12 min. and did the same thing does this sound like the txv is sticking?
The system is a 410a 2ton coleman I will get model # next trip over. I pulled disconnect and swithed to emerg. heat. Thanks for any help

[sedgy]

hi tbone,
sounds like you have overgassed the system, you should get a fridge firm to come out to it and re- claim the gas

[Bigfreeze]

Not a blocked expansion valve as suction pressure would drop. Sounds like heat dispersion from the condenser is compromised some how. Check filters for blockages or a slow fan speed.

[Mick13]

sounds like your indoor fan is dropping out

[ttbone72]

Ok was thinking suction would drop but... I did notice when I pulled the pleated filter out during the first 10 min of running the head pressure would fall about 5-8 psi but would still start to climb fan speed is on med. speed and if I rember right they do have the vent in two rooms which are not used closed off do you think this can contribute to the problem?
This is in a double wide with vents in the ceiling, about 6' of 16" flex from airhandler to whatever trunk line (if any). Thanks for the input will go back 2marrow and dig somemore into it



Not a blocked expansion valve as suction pressure would drop. Sounds like heat dispersion from the condenser is compromised some how. Check filters for blockages or a slow fan speed.

[a/c.nick]

whats your outdoor and indoor temp? some units just dont work when its cold

[Mick13]

i will (almost) bet everything i own that your indoor fan motor is dropping out.

i would be investigating the fan motor/controls, indoor coil sensor come off the coil maybe....

[ttbone72]

will check coil sensor 2day; the fan was not cutting out i was removeing the filter and looking out the window at the gauges when i watched the psi drop 5-8 psi for about 5 min then start climbing again but no change in the motor.
indoor temp was about 71 outdoor temp about 42


i will (almost) bet everything i own that your indoor fan motor is dropping out.

i would be investigating the fan motor/controls, indoor coil sensor come off the coil maybe....

[monkey spanners]

Have read about R410A txv failures where the power element charge leaks into the system, running the system in one mode allows high pressure gas into the element through the leak, once mode change from heating to cooling or vice versa the system works ok until the gas leaks back out of the power element that is now in a low pressure part of the system.

Note this is not a leak of refrigerant out of the system but just into the bellows of the txv.

But as the others have said it could be a number of things...

[Bigfreeze]

Personally I'd go to the most obvious and least intrusive option first. Go to the scenario of least restriction to air flow. Open vents to last and remove filters. If that solves the rising head pressure then put everything back one by one to find the source. If it hasn't solved it then I would get a flashlight and get a good look at the condenser. It could just be covered in crap from years of running which would restrict heat transfer. Also check the fan speed. Even if it is running it could be running slow.

If its not that, then you're into a problem in the fridge circuit but I'd be suprised if one of the first two checks didn't solve it.

[Mick13]

if the problem was blocked filters, blocked coil, or blocked outlets the head pressure would rise from the moment the system is started, not run fine for 12 minutes and then skyrocket.

u said when u removed the filter the head pressure dropped 5-8 psi, and u had the filter out when it sky rocketed - that rules out the filter.

for something to be running OK for 12 mins then have the head pressure go through the roof - means there is a drastic change, the coil cant just go from being clean to dirty instantly, which is why im positive airflow is somehow stopping.

the only time iv seen something like this was caused by the indoor fan stopping.

but it could also be something else restricting the airflow, are their zones on the system?

[ttbone72]

UPDATE. I made it back over to the unit last night; had 2 rooms with vents closed and bathroom 1/2 closed. opened all vents pulled filter out double checked coil no blockage (system is about 1 1/2 years old) checked fan rotation it's correct. ran system again about 12 min head pressure started to climb made it to 600 psi then compressor changed sounds from straining to allmost like high pressure relief but high pressure dropped to 330 suction stayed about 118 the whole time; change maybe 5 psi. it stayed running for about 5 min then comprssor went out on over load.
The indoor fan ran the whole time.

[Mick13]

Does it have a scroll compressor? some scrolls have an internal pressure relief valve from high to low.

Do you remember what the liquid line temperature was when the head pressure was up?

[a/c.nick]

we had a problem like this on an mitsi heavy industry . it turned out to be a block in the expansion valve, and have come across faulty eev solenoids in fujitsu units.

[beatnik]

Sedgy might be right.I had a very similar problem with a Fujitsu ducted system. Old and R22 but would work fine for 5-10 minutes then pressure would sky-rocket but suction still the same. When it got to (from memory) around 575-600psi a hissing sound like pressure relief would come from inside the compressor. This problem only raised itself coming into spring/summer. Turns out the unit had 5 kilos too much refrigerant. I reclaimed and charged in correct amount and fixed the problem.

[Gary]

Sounds like an overcharge to me... but we don't have much info to go on.

For starters, we need the model numbers for both indoor and outdoor units.

[Gary]

Next, we need the entering and leaving air temperatures for each coil (measured near the coil).

Then we need the liquid and suction line temperatures near the outdoor unit, along with the high and low side pressures.

[sedgy]

HI ALL , WELL AS YOU KNOW i AM NOT BYAST BUT i AGREE WITH THE YOUNGSTER SEDGY WHO ANSWERED FIRST,= SEDGYS FATHER

[mikeref]

Pull the gas and weigh in correct amount, at least that is a starting point and eliminates 2 possibilities. Think your indoor fan is crook. ( As has been said before)