HVAC techs: Should I replace A/C crankcase heater?

Question

I have a Trane XL 1200 split system air conditioner (cooling only, no heat pump).  It's 14 years old.

Earlier this week, it tripped the circuit breaker.  The breaker would not stay reset, even with the thermostat set to "off".  The HVAC technician immediately suspected a shorted crankcase heater.  He disconnected it, the breaker stayed "on", and it's been working fine ever since.

He's telling me that I don't have to have the crankcase heater replaced.  This is a residential application, and I won't be running the A/C when the outside temperature is below 50 degrees F.  He's also concerned that there's some risk to the other components when opening up a 14-year-old unit to replace the heater.  I'll add that the outside unit is on the southeast side of the house, and gets both direct sunlight, and sunlight reflected from two stucco walls.  It's an unusually warm location.

I'm looking for a second opinion.  What am I risking without a working crankcase heater?  I'd just as soon save the money, but not if it means I blow up the compressor in a couple of months...

Thoughts and opinions?

Anonym · Accepted Answer

If your compressor DOES NOT have an independent crankcase heater at all (belly band or bullet style in a well) and all you have is a single pole contactor - one contact and the other side barred - then it is incorrect to believe that the windings inside the compressor are energized at all times and heating the compressor.  Single phase motors (1 line of power in 1 line out) can be safely stopped by breaking only one line of power.  You can break both lines by using a two pole contactor; however, the minimum is one leg/line/pole.  The Manufacturers use single pole contactors as a production/money saving feature (they cost less per unit than installing a 2 pole - less cost = more profit to them and still does the job).  In this case, with no independent crank case heater, you gain/loose nothing by leaving the condensing unit on.  There is no current flow through the motor windings as you have broken the circuit ( if there was current flow you then would have an unintentional circuit and a defective/grounded winding(s)).  No current flow means no cost to you.

thum · Answer

Crankcase Heater

? · Answer

If you live someplace where it gets cold in the winter,  You need to have a CCH.  Its meant to prevent migration of oil from the compressor into the system during OFF periods in winter.
I had a CCH fail in a 30 Ton Chiller at my work.  I ended up having to replace an expansion valve
because of it.  A costly repair.  You dont have to replace the heater with that exact one.  They make heaters that wrap around the bottom of the compressor that do just fine.  I have never replaced a cartrige type that you must have, but I'm pretty certain that changing one of these heaters is not a risk to other components.

Bethany · Answer

This Site Might Help You.

RE:
HVAC techs: Should I replace A/C crankcase heater?
I have a Trane XL 1200 split system air conditioner (cooling only, no heat pump).  It&#39;s 14 years old.

Earlier this week, it tripped the circuit breaker.  The breaker would not stay reset, even with the thermostat set to &quot;off&quot;.  The HVAC technician immediately suspected a shorted...

bigdaddy · Answer

what does he mean opening the system? it probably just had a band type heater that wrapped around the compressor. it probably wont hurt anything but you never know. a crankcase heater should not be that expensive. if he lead you to believe the newer residential units dont have crankcase heaters he is wrong. they are wired with 1 leg of the 240 going thru the compressor motor winding all the time to keep the comp warm

Dan B · Answer

This is one site's explanation.  Diluted crankcase oil which leads to compressor bearing failure:

During the normal operation of a central air conditioner or heat pump the compressor is both drawing "suction" from the evaporator and "discharging" hot gas into the condenser coil. While running, there is enough heat being generated by the compressor running to keep from creating refrigerant migration from occurring. Refrigerant vapor always migrates to the coldest part of the system - the compressor. The refrigerant "migrates" to the compressor crankcase where it is attracted to the compressor oil. This refrigerant vapor "condenses" ( turns back to a liquid during the "off cycle") then on the next start of the compressor, the oil is in a watery state and washes the bearings out, which leads to locked up, frozen or totally burnt out compressors. This is especially true of Heat Pumps. Some manufacturers of AC equipment install crankcase heaters either in the compressor or mount them externally around the base of the compressor. The (2) wires of the heater is wired directly to the 230 Volt input side of the contactor from the main power supply, and is always supplying 230 volts of power to the heater. The result is a warmed lower section of the compressor which drives any refrigerant that gathers there back into the system rather than to allow condensation in the crankcase. This is an over simplification, but we think you get the idea.

Anonym · Answer

Trane Heater

Polar Bear · Answer

Anywhere under about 70F if the unit sits without cycling operation, the refrigerant will migrate under the oil in the bottom of the compressor..... You say its working ever since. I'd like to know what the running load amperage is running about now.

Anonym · Answer

i dont know where you live but i live in south louisiana and most here dont even have a heater.

HVAC techs: Should I replace A/C crankcase heater?

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