Replacing compressor motor (going from 3 wire to 4 wire) and question about wire colors


The compressor is the "engine" of the AC system. It, and a few valves, and the condenser fan, comprise all the active portions. Everything else is passive. The compressor is an electrical motor connected to a precision pump. The pump has to be lubricated by sufficient refrigerant (Freon or substitutes). If a compressor seizes, it may burn out the electrical motor, causing the electrical windings to short out.

Long story short, a failed compressor may be a reason for system replacement. You would be well advised to get a second opinion from another contractor. Get quotes for both repair and replacement.

Another reason to replace the system, is the mandated phase-out of R22 refrigerant. If your system is older than 5 years, it probably uses R22. While an existing unit doesn't need to be replaced, per se, because of the phase out, practically, it will, due to the price of the refrigerant. I just paid $5/ounce for my system...

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Figured this out! I hope this answer posted here helps someone else. The real topic here is "converting from a 3 to 4 wire motor.

First of all, a shout out to Solar Supply, Inc. in San Marcos, TX for matching the Mars 10204 motor with my GE for about 85 bucks.

The first thing he did when I got it was grab a capacitor and add it to the box. I thought, "I wonder why, I already have one?" Well, now that I compared both diagrams it makes sense.

The old motor's orange line was connected to one of 3 leads on the capacitor. From that line I noticed that there was a YELLOW line that went to the terminal block. I deduced that orange was analogous to yellow on the new motor. Black? That was easy, at least one thing was obvious.

That leaves the brown and brown/white pair. It finally dawned on me that these were to go on the new, separate capacitor that the guy at Solar gave me. I'm assuming that having a dedicated capacitor for the fan motor is an overall...

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You are going from a 3 wire configuration to a 4 wire config. Not a big deal and it is done all the time.

You are changing the run capacitor out so that is good.

Pull the lead off (after discharging) the fan side of the dual run capacitor. Leave the rest of it alone. The common and herm side are working for the compressor only and we just leave them be.

Take the two brown wires (br and br/wht) and put one on each end of the new capacitor. Doesn't matter which side.

The other two leads go to the load side of the contactor.

If you have a heat pump one lead will probably go to the contactor and another to the defrost board relay.

Just pay attention to where the wires are now and take pics, draw anything to keep it straight.

Also a tip: don't pull the old motor off until you pull the fan blade off - if at all possible. It is easier to pull the blade and less likely...

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Turn off electrical power to the air compressor switch at the main electrical panel. Tag or otherwise mark the circuit breaker or switch to prevent inadvertent restoration of power.

Remove air compressor pressure switch cover. The cover may have screws near the base or a crown nut depending on the manufacturer. Remove retaining nuts with an adjustable wrench; remove screws with the appropriate tip screwdriver.

Perform a voltage test to verify the absence of power at the switch. The wires from the main electrical panel are connected to the L1 and L2 terminals of the pressure switch. Place one probe of the voltage tester on L1 and the other probe on L2.

Insert the threaded end of the cable clamp into the open slot of the switch body. Attach the retaining nut from the inside of the switch. Tighten the nut in a clockwise direction with the slip joint pliers.

Measure the cable length required to connect the air compressor motor with the pressure...

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Air Compressor Electric Motor

Electrical Question: How is a 3 phase air compressor wired and where do the wires go? We have a Saylor Beall air compressor we are trying to get wired up. It ran fine at the previous shop and then we moved it to this shop. The motor is 3 phase and it appears to be wired according to the diagram for the low voltage 220. The label shows that it can be wired for 220 or 460. It is all wired and hooked up to the controller, but here is where we are having problems, we cant get it to start, it only hums. The motor starter is a Cutler Hammer # A10CNO. The wires from our shop circuit breaker has 2 yellow hot wires at 120 volts each, 1 white neutral wire and 1 green ground wire. Is it possible to wire the compressor with this combination of wires and where do they go? When the compressor was moved it was simply unplugged from the wall and moved, all pressure switches and motor wires are in their same locations as before.

This electrical...

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Capacitors are important components for a


. Fitting the right or specific rated capacitors is crucial. Installing a capacitor which is either under or oversized can end up damaging the motor. Generally capacitors have a tolerance of (+ or -) 5 and 10%. In case the capacitor is a 12 micro farads (uf), using a 10 uf or a 14 uf should suffice. The capacitor rating can be measured using a capacitance meter.

To know more about capacitors problems, below are a few questions answered by Experts.

Does a failing 35/5 MFD, 370 VAC run capacitor on the home AC unit need to be discharged before removing it?

It would be a good idea to disconnect the leads from it. Next eye protection and gloves should be worn and using a screwdriver the two terminals should be shorted to each other. One should be prepared for sparks while doing so. After doing this a couple of times, the capacitor may become safe to handle. Additionally based on the capacitor condition it...

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My dad has removed both the start and run capacitors on his 6.5 hp ac motor but due to previous strokes and health problems his sketch didn't match when he tried to put the 6 wires back on. I went and checked and the new cap he bought checks good (run cap) and the start cap checks good but I tried several different ways and can get it to start and run un til it is charged with air pressure then it will not start back up it trips off the protective breaker. so it appears that the starting cap is not wired correctly. to save a lot of trial and error I was wondering if someone had any pics of theirs so i can see the wire colors?
the model of the ac motor is magnetek century ac motor model # 8-186372-01 3450 rpm.
right now I have an orange and white wire on the run cap (which has the lower capacitance value ) don't remember but maybe 30 micro farad.
on the starting cap there are 4 wires a white, blue,blk,and red.

since I never saw it before he disassembled it it may have...

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How to hook up an electric motor start or run capacitor:

This article gives electric motor start-run capacitor installation & wiring instructions for electric motor capacitors designed to start & run an electric motor such as an AC compressor, heat pump compressor or a fan motor, and how to wire up a hard-starting air conditioner compressor motor, fan motor, to get an air conditioner, heat pump, refrigerator, or freezer compressor or other electric motor (such as a well pump) going.

This electric motor capacitor article series explains the selection, installation, testing, & use of electric motor starter start and run capacitors used on various electric motors found in or at buildings such as air conditioner compressors, fan motors, some well pumps and some heating equipment.

Green links show where you are. ©...

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Air compressor motor wiring diagram – Campbell Hausfeld EX8007

Wiring Diagrams INDEX LEGEND UNIT TYPE VOLTAGE (1 Ph-60 Hz) FIGURE NO. LABEL DIAGRAM COMP — Compressor Motor CON — (2) Circuit Plug Cap CR — Compressor Relay Single AIR-ZENITH OB1 Compressor Wiring Diagram Wiring diagram for single OB1 compressor with Air-Zenith 80A relay and Air-Zenith adjustable pressure switch. My Question is about checking the wiring on my A/C compressor and capacitor. The compressor has five wires coming out of it and they connect as

Atlas Air Compressor Wiring Diagram Documents >

New Members: GAY POO FUCK DIRTY MESS POO ASS HOLE 22dsadasdas444d joined 29 seconds ago. GAY POO FUCK DIRTY MESS POO ASS HOLE 22dasdasfsdfds444 joined 1 minute ago. can you help me with the wiring of a compressor motor for 220V on the name tag DOERR wiring to 240V input Can you direct me to where to find/get the wiring diagram Updated: 2012-07-11 ATLAS...

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HVAC - How to Replace the Fan Motor in the Compressor Unit.

Shared Knowledge

"HVAC - High Voltage Air Conditioning"

"How to Replace the Fan Motor in the Compressor Unit"

Summary: if the fan motor on top of the outside compressor unit seizes or otherwise fails, the coils surrounding the compressor will not be cooled and the compressor will shut down after a while to self-protect itself. Replacement of the fan motor is a do-it-yourself (DIY) but involves many different steps and may require cutting wires and soldering.

Bad fan in compressor unit:

Never replace parts unless you are sure or think you are sure the part is defective.

If you have not already done so, read "HVAC - Outside Compressor or Fan Not Starting or Running"


HVAC has 240, death, alternating current (AC) voltage.

Do not attempt any do-it-yourself (DIY) repairs on HVAC if you have never worked with or around high voltage.


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I'm sorry for the long list of possibilities

Drive Motor

Every air conditioner has a circulation fan motor also called a drive motor. The motor has two fan blades, on one side the blade draws outside air over the condensing coil to dissipate the heat. On the other side of the motor there is a fan blade drawing room air over the evaporator coil. If the fan does not run, the drive motor may be defective.

Dual Shaft Fan Motor

Every air conditioner has a circulation fan motor also called a dual shaft fan motor. The motor has two fan blades, on one side the blade draws outside air over the condensing coil to dissipate the heat. On the other side of the dual shaft fan motor there is a fan blade drawing room air over the evaporator coil. If the fan does not run, the dual shaft fan motor may be defective.

Fan Motor

If the fan does not run the fan motor may be burned out or worn out. The fan blades should spin very freely, if the blade doesn't spin...

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Customer: replied 4 years ago.

Thanks, i'll give it a try. The mechanic who rebiult and intalled the tranny has been the one who has been here every day. Today he checked EVERY wire in the harnness for continuity and said all were good.

BTW, the engine did not stall w/ the spare coil. I shut off the engine to install a new coil and that is when it did'nt crank again,,,,even after re-installing the old spare coil.

This problem occured w/ installing the newly rebuilt tranny. the first time i tried to crank it it would'nt start.

I intend to FULLY check tommorrow for pinced/broken/unhooked wires. We have done this several times but it would'nt hurt to check again.

I don't have a chip on my ignition key, but the truck acts like i am using a spare key by not firing. My truck is too old for that technology, but that is the symptoms.

There HAS to be something that is causing my truck not to fire anymore. Everything that we...

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Not being able to obtain a diagram from the manufacturer this is the only way to solve the issue. I'm sure it will work and you really don't have an alternative. Wire it as directed and see for yourself. Like I said the most that could happen is that you'll trip a breaker. Please check the link for a 6 wire dual voltage diagram. As you can see the diagram shows that the direction can be reversed. In your application not wanting the compressor to turn in reverse, the manufacturer had their motors made with the T-8 lead connected internally, leaving the 5 leads you have and by using this diagram with the 5 leads the way I suggested is the only possibility. A lot of effort went into getting this solution for you. If you don't like the answer, I don't know what else can be offered.

Edited by Mike G. on 8/27/2010 at 9:35 PM...

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Okay, lets take care of this once and for all. I want you to remove the battery and move the fuse box/front control module out if the way. Here is the info for removing the fuse box/front control module:


Disconnect the negative and positive battery cables. Remove the battery thermal guard from the vehicle. Refer to the Battery section for the procedure. Remove the battery from the vehicle. Refer to the Battery section for the procedure. Using a flat-bladed screwdriver, twist the Integrated Power Module (IPM) bracket retaining latch outward to free the intelligent power module from its mounting bracket.

Rotate the IPM counter-clockwise to access and disconnect the various electrical connectors.

Free the IPM from its mounting bracket by removing the IPM bracket clips from the hinge. A screwdriver slipped up from under the hinge will free the clips.

You dont have to remove it all the way out, mostly just so we can gain access to the...

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