Mitsubishi MXZ3C30NAHZ4U1 – High Pressure Protection
Note sure if this can be posted here – just looking for advice…
I have a Mitsubishi MXZ3C30NAHZ4U1 system installed, with two in celling cassettes (upstairs), and one wall unit (downstairs) about 7 months ago. We’ve had a couple cold days (20s), and I noticed the downstairs unit was not blowing hot air, rather warm air, while the upstairs was blowing very warm (hot) air and reaching multiple degrees over the set temp (70).
After a couple days of it blowing warm air I called to have it looked at (different company than install – long story not relevant), and his initial walk through was everything was fine no issue. I told him what happens and since today is in the 40s it does not seem as bad. —- Also note – I had a lighting strike very close to home this summer, blew out cable modem, fire alarms went off, etc… so I mentioned that as maybe the control board could be an issue? —- He went to the outdoor unit and found an error code (unit is operating, LED 1 (red – blinks twice), LED 2 (yellow – lighted)
He hooked up his gauges to check pressure and found this. Low pressure side is very high.
He said the first step is to drain the whole system and weigh it, because the system is over charged. Since the two units up stairs are working (20ft+ run and 40ft+ run), and the downstairs one (6ishft run), is not working properly, it makes sense. I know nothing about this, so it sounded right. Then…he said its $620 so drain weigh and replace, and he’s not even sure that’s the problem, as it could be the unit, or controller board…etc etc.
This is when I went online and looked at the manual for the error code and I didn’t see anything about an overcharge being mentioned. Some googling tells me it could be valve? in the unit itself… I’m not sure what’s next. Does draining the system, weighing it and replacing it make sense? Is $620, right amount to do that? Any suggestions?
I do notice the upstairs units blowing hot air, even when there temp has been met (set for 67 – but currently blowing hot air and reading 70 on KUMO app) – Reading online tells me if the system is over charged that would make sense, because the line temp? pressure? is different so the unit kicks on? – again I know nothing, just trying to mention ‘oddities’
Note- I did check all the airlifters on the units are all pretty clean.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
I think you need to find a different service company!
$650 for what should be less than an hours work and zero parts seems like a I don't want to work on your unit pricing.
Note if the technician were to close the low side valve on the unit and open both valves on the gage set the low side gage would then read the high side pressure and show the very scary reading in the photo. I am not saying it is a scam just get a second opinion.
Walta
lol… accounting for some mechanical error on the low side of the gauges (since the reading is so far off normal range) the low and high side are of equal pressure. Assuming the compressor is running no amount of refrigerant alone will cause such readings. You have a faulty compressor or ev in the outdoor unit.. most likely also the unit is severely overcharged too…
And Walta- it takes couple hours to recapture the gas properly. So in some markets $650 is not far fetched for that service … not that it is needed in this case though…