mitsubishi 1.5 ton split system issues

[zeke2u]

Hello All - I'm having issues with the compressor, I believe. It's a relatively new (a little over 1 year) system that I installed (http://www.refrigeration-engineer.com/forums/showthread.php?37237-mitsubishi-1-5-ton-split-system-install&p=267737#post267737). When the temperature falls below freezing, the compressor seems to make strange noises. It still works but during the heating stage, just before the system goes into defrost, my indoor unit transmits a very loud screeching sound. I think it is coming from the compressor but is transmitted through the fluid and to the evaporator. At all other times during the cycle, the compressor is quiet.

I also suspect that there is not the correct amount of refrigerant in the unit. I had an HVAC company that installs Mitsubishi's "service" my system, this past October, but it wasn't cold enough for the screeching sound and the technician seemed to think that everything was operating properly and that it might just need a little more refrigerant. He did not take any measurements of how much refrigerant (mass) was in the system - he only took pressure readings. Anyway, he added about a half-pound of refrigerant and did a not very sophisticated leak test on all the fittings (sprayed liquid from a spray-bottle and charged me $39.95 on top of the service-call charge). This primitive 'leak-test' produced no positive results. I know that I made very good flarings, but I also know that there is no such thing as a joint that doesn't leak - and there was no measurement made of the actual amount of refrigerant that was added. I'm uncertain, now, as to which factors more into my higher electric bills - incorrect amount of refrigerant or faulty compressor?

So, I've also noticed a large increase in current usage - my electrical bill doubled compared to the same month last year (1750 kWh vs. 1000 kWh). I'd like to be able to repair this, myself, but don't know if I have the resources, technological and mental, to accomplish this...I have pressure gauges, but no way to actually measure the actual amount of refrigerant in my system. I'm still keeping my house at 18º C, but it's presently snowing and about -10º C outdoors, where do I start?

[monkey spanners]

Turn it off and don't run it till the refrigerant charge has been checked as being correct. The refrigerant needs to be weighed in, you can not test the charge by pressures on minisplits.

What vacuum level did you pull the system down to when you installed it?

[zeke2u]

Thanks for the quick response - I can't quantify a vacuum level. I did use a 8890 Welch dual stage rotary vane mechanical vacuum pump (spec'd @ 1/10 Torr.) at about 15º C for approximately 3 hours. How critical is it that I turn it off? It's been running constantly for the past 3 months.....

[monkey spanners]

How critical is it that I turn it off? It's been running constantly for the past 3 months.....

Well you said the compressor is intermittently making a screeching noise, its nearly doubled its electrical consumption, and a tech has charged approximately 250g additional refrigerant you're not even sure the system needs so i though turning it off would be a good idea to prevent any damage from being done or made worse.
Now if you are happy to use the systems continued operation for the last three months to satisfy you that my concerns are unfounded please feel free to carry on as you are and wait on the opinions of some other forum members.

[zeke2u]

Well, I think it's the compressor making the noise - I'm not certain. And, it was making this noise before the tech added refrigerant. I'm just not certain about anything - and I'm sorry if I gave the impression that I was not taking your recommendations seriously. I know I don't want to have the same tech' come and try to diagnose what the problem is. So, what do I do after I shut the system down? Should I make the attempt to get all the refrigerant back into the outdoor condenser, before I shut it off?

[install monkey]

morning zeke- indoor screetching- u do get a whooshing noise on start up with gas throttling through the indoor unit- but that will stop within about 30 seconds, my 3.5kw daikin (13000btu) is used frequently and my daily power consumption is 18kwh . so only 15kwh without it
in heating mode at maximum demand your unit should only pull about 12amp - outdoor unit will state minimum fuse rating- as a guide to what it can pull
if there was any issue with excessive comp current then the unit would generate a fault- check filters are clean, doors are shut, maybe new light fittings,immersion heater could be the cause of your higher utility bills

[zeke2u]

OK - I shut the system down. I suppose now is a good time to have someone come and collect/measure the r410? Then what - how do I diagnose what's causing the noise? Is it possible that the added refrigerant is what caused the current draw to increase or do I assume the compressor is gone? Any ideas of what they sell for? Are they something a person with decent mechanical abilities can install or should I leave this to the experts?

[zeke2u]

Hi install monkey - Actually it's late in the afternoon here - snowing, -13º C and falling. The noise is more of a screech, along with the whooshing that normally occurs when it goes into defrost. The screeching only occurs before it goes into defrost, while it's still heating. When it goes from defrost to heating, there is no screeching. IIRC, the outdoor unit can pull 20 amps @ 240 V. I know the filters are clean, and I'm very careful about leaving doors open (I live alone). I have on-demand electric water heat and I haven't changed my bathing habits that much! There's no flashing lights or error codes occurring on the indoor controller. It's an 18,000 Btu unit. Anyway, I took monkey spanners advice and shut the system down - hopefully, if there is compressor damage, it can be rectified without a lot of monetary depletion.....say no more!

[install monkey]

try and get the repair under a warranty claim

[zeke2u]

OK, some more information. An HVAC service tech' came, yesterday, and looked at my Mitsubishi. I started it up, but knew it wouldn't make the noises it has been making because it only seems to do this when the temperature falls below freezing. Yesterday the ambient temperature was a little above freezing, 5º C. He attached his gauges and took a current reading: "outdoor unit at 5 amps, 400-550 psi, heating output normal.
He commented that it appears to be running normally. I let him watch a video that I had taken earlier, when it was cold, that recorded the sound at both the indoor air handler and outdoors at the compressor. He called Mitsubishi, reported the complaint, and waited for a reply, which never came.

This was the same technician that added r410 (somewhere between 8-16 oz.) without actually measuring the amount in the unit. I had scheduled an appointment, with his manager, for someone to diagnose the abnormal sounds coming from, I think, the compressor.

Anyway, he left and said he'll schedule another visit when it's colder and after he hears from Mitsubishi.

If anyone is interested, here's two youtube links that I uploaded which document the sounds coming from both the indoor and outdoor units. I also forwarded these videos to the HVAC shop, hoping that they will forward them to Mitsubishi so that they can have a better idea of the problem.....

https://www.youtube.com/watch?v=vJzX1RD1SM0
https://www.youtube.com/watch?v=F_dd_lNS2l4&feature=youtu.be