How to kill a compressor in 2 years

Harvey Ramer

Just went out on a new service call the other day. Typical 2.5 ton heat pump system. Cleaned coils and traps and all the normal stuff, then threw my gauges on. 40° evap temp but no superheat. Ok. measured airflow and it is scarcely 300 cfm per ton. Checked the fan speed and both the heat and cool wires are on the low tap. Ugh. Set the proper airflow for both cooling and heating and back to the gauges. Higher evap temp but no superheat. Orfice system. Ok, time for the recovery cyclinder. As I start removing refrigerant the condenser pressure starts dropping even while I still don't have any superheat. By the time I had a 10° delta-t on the condenser, no superheat and a high evap temp, at the proper cfm, my heart began to sink. Doing due diligence, I recovered all the Freon and checked the orfices for the proper size. They were. I weighed the proper charge back in, 8.75lbs and left the other 6lbs that I recovered in the jug.

In a nut shell, we had a bad compressor from the overcharge and the low fan speed in hp mode.

The homeowner was incredibly angry. I would be to! Come to find out, out of three quotes he chose the one that was 2k less than the others. To bad.

ratio

I pulled 16# out of an 8# system once. Removed the suction filter dryer, removed two(!) extra liquid line filter dryers, replaced the plugged liquid line dryer (Yup, that's number three in the liquid line), dumped 8# back in, and she's still working today!

Harvey Ramer

Extra refrigerant always fixes things, lol!

JUGHNE

I have seen several heat pumps die for lack of return air in the heating mode. Some were installed on existing duct that barely had enough air flow for old gas furnaces (run high temp rise because of low air flow).
Another cause was the electrostatic air filter......as advertised by Paul Harvey if anyone knows of him. These filters trap dirt inside that not is visible. People rinse them off and actually create mud inside the filter. Almost a power washer is needed to really clean them well. They may be an excellent filter but if not completely cleaned will retain a lot of dirt. And homeowner thinks it is time to wash out but it is winter/cold outside and I'll do it later.....which comes too much later.
So a full case of pleated throw away filters next to the furnace will entice people to do the quick change. IMO

njtommy

I love pulling extra refrigerant out of systems. Last week on a unit tag said 12lbs I pulled out 30lbs out of r22. Yup if it wasn't for the hot gas bypass opening and a larger accumulator it would of just banged out on high head. Found bad power head on txv.

ratio

I always wonder how that happens. It's like, "Welp, the suction pressure is low. I'll just jack in lots of juice....done!" Nothing's changed, but now I'm done? smh.

Dave0176

All that free R22 lol

ChrisJ

ratio said:

I always wonder how that happens. It's like, "Welp, the suction pressure is low. I'll just jack in lots of juice....done!" Nothing's changed, but now I'm done? smh.

People constantly make jokes about homeowners saying "it just needs freon". How about all the techs going around thinking the same way when they should know better?

njtommy

They should know better. But beer can cold and warm to the touch is the some of these guys roll.

pecmsg

Should have removed the compressor and installed a liquid pump!

Harvey Ramer

A lot of units get overcharged at installaton. When starting up in a hot house, txv is out of its performance range. Basically it's just hanging wide open and the compressor is blowing refrigerant through. Condenser pressure and subcooling are usually lower than the manufacturer charging chart indicates they should be even when you are using the return wet bulb to make the calculations. If you add refrigerant to meet the chart in this scenario, you will be overcharged. Manufacturers know it and while they make no mention of it in the manual, they say come back the next day to take readings.

Paul S_3

irecently replaced a compressor in a low temp walk in box.....condensing unit (404a) was rated at about 7k btus at a -20F evap temp....evap below condensing unit....about 40 Feet ....no traps ....get this suction line size was 1 5/8".... system is 8 years old and i installed the 5th compressor customer got frustrated from previous contractor not showing up on time.....replaced suction line ...7/8"...added an oil seperator.....installed 2 traps....drained about a gallon of oil out of the evap....and probably just as much out of the accumulator....customer thought a compressor only lasts a few years....hopefully i covered all my bases to prevent another bad compressor and keep oil in the compressor.

EBEBRATT-Ed

I got called on a 1 1/2 ton split R-22 lack of cooling call. I get on the roof and it's running no heat coming from condenser. I put gages on and suction is 90 head is 150 so I'm thinking bad compressor. Sight glass in the liquid line--thought this was strange and it was clear. Amped out compressor and it's pulling full load so now I'm wondering if it's bad. Checked ahu and it is an orfice system so I started pulling gas out and pulling gas out and pulling gas out and the thing was fine.

can't fix stupid

JUGHNE

2 ton AC cond on roof not cooling, putting out hot air.
Had high head , don't recall low side. Walked over to the overhead service with amp clamp meter and found an extra 40 amps more than you would expect from the building's standard load.

Electric furnace had AC coil down stream of heater elements.
2 stuck on and cycling on OL. It was actually the electric utility company office.........no profit there for them on that day.

Harvey Ramer

JUGHNE said:

2 ton AC cond on roof not cooling, putting out hot air.
Had high head , don't recall low side. Walked over to the overhead service with amp clamp meter and found an extra 40 amps more than you would expect from the building's standard load.

Electric furnace had AC coil down stream of heater elements.
2 stuck on and cycling on OL. It was actually the electric utility company office.........no profit there for them on that day.

I ran into the same thing in a split system. Only difference being, there was a short in the thermostat cable running to the outdoor condensor, that in turn, energized the backup electric coils. In this instance the coils were after the evap coil though.

ratio

And I just did that intentionally to two air handlers a week ago. Two 7-1/2 ton heat pumps were having trouble with humidity, 70-80% RH at 70*. I already knew they wanted the cheapest solution possible (reuse all the old junk, can't afford to drop the grid to repitch the drains to something better than 1" in 50', etc.), so a TH8321R bangs in the reheat and compressor, we call that "dehumidification mode".

Solid_Fuel_Man

Gotta love the pay to cool it, pay to heat it back up, then out the diffuser it comes mentality. Had the same thing happening at a medical facility we service. Reheat coils after evap in attic handlers, drawing 65amps while it's 80 outside and the r22 is flowing. One pam-1 relay layer and that won't happen again.

Taylor

John Mills_5

Our record is 27# out of a 3 ton HP.

Anyway, on blower speeds, gotta look at the blower performance chart and measure ESP to know what is right. Up here with big blowers, we often are low on cooling with furnace. Usually air handlers with heat pumps that isn't the case but you never know.

unclejohn

Took about 10 pounds out of someones else's new install that keep going out on high head, imagine that. Then the customer got even madder when i charged him to remove the extra freon.But but why do I have to pay you too take it out?