How to Install an AC Compressor in Vehicles

by Contributing WriterUpdated June 12, 2017

The compressor in your Vehicles air conditioning system drives refrigerant through the A/C system and pressurizes the refrigerant gas so it can absorb heat energy. The compressor has a clutch mechanism that allows it to kick in and out, depending on the temperature in the passenger compartment. It has a belt drive and either a single belt or serpentine belt, depending on the year and engine in your Vehicles. There is a high-pressure hose that pushes refrigerant to the evaporator housing and a low-pressure side that returns refrigerant from the condenser.

Under The Hood:

 How to Install an AC Compressor in a Chevy S-10

Evacuate the air conditioning system by taking the truck to a garage or oil change facility. They will usually evacuate the system for free, as they get compensated for collecting it. It is not wise or legal to vent the freon into the atmosphere.

Disconnect the battery by turning the positive terminal bolt in a counterclockwise direction.

Disconnect the freon coolant lines from the compressor by turning the line nuts counterclockwise with a line wrench. There may be latent pressure form the evacuation that will escape and cause a hissing sound, but it should not alarm you. Set the lines aside, but leave them attached to the rest of the system.

Disconnect the wiring harness adapter plug on the top of the compressor by pulling the blade connector free of the terminal.

Remove the primary drive belt from the compressor pulley wheel by pushing on the tension pulley arm firmly until there is enough slack to remove it from the idle pulley wheel. Release the tension pulley and there will now be enough slack to remove the belt from the compressor pulley wheel.

Remove the compressor by turning all of the mount nuts counterclockwise, while holding the hex head bolts in place with another socket wrench. Once free from the bolts, the compressor comes directly out of the engine compartment.

Replace the compressor by positioning it into the mount and securing the mount bolts and nuts clockwise. Reattach the wiring harness terminal and freon lines (check the nut gaskets for damage). Wrap the primary drive belt over the compressor pulley wheel, grooves down. Press the tension pulley arm and slide the belt back underneath the idle pulley. Release the pulley and the belt will tighten to the proper tension.

Reattach the battery terminal bolt, start the car, and recharge the air conditioning system with the proper amount of freon, in this case about two pounds. Add additional lubricant for the new compressor.

Items you will need

  • Socket set

  • Screwdrivers

  • Line wrench

 How to Install an AC Compressor in a Honda CRV

Removing the Old Compressor

Take the CRV to a licensed air conditioning technician to have the air conditioning system discharged. 9Given the intense pressure the system is under and the environmental dangers of the refrigerant, this should never be attempted by an amateur.)

Disconnect the car's negative battery cable by loosening its clamp nut with a wrench. Set the parking brake and block the rear wheels with chocks. Raise the car's front end using a jack, place jack stands under the car and and lower the car onto the stands.

Take off the power steering drive belt by loosening the mounting bolts/locknuts, turning the adjuster bolts to loosen the belt tension and slipping the belt off its pulleys. Use the same procedure to remove the alternator/compressor drive belt. Make a note of how the belts were routed on the pulleys; there is usually a printed diagram on the side of the engine compartment.

Remove the battery ground strap bolt for the car's alternator and the cover from the radiator crossmember, then remove the upper radiator mounting brackets and rubber insulators. Remove the alternator's mounting bolts, disconnect the black wire and the electrical connector, and detach the harness clip to remove the alternator.

Remove the splash shield from underneath the engine compartment by removing the fasteners from the right and left sides.

Detach the coolant reservoir by disconnecting the reservoir hose from the radiator filler neck (plug the hose to keep it from leaking), by removing the mounting bolts and lifting the reservoir out of the engine compartment.

Disconnect the compressor clutch wiring harness. Disconnect the refrigerant lines from the compressor and plug the open fittings to prevent contaminants from entering. Remove the compressor's mounting bolts from the bracket, and guide the compressor carefully out the opening below the engine compartment.

Installing the New Compressor

Transfer the clutch from the old compressor to the new one if the old compressor does not have one, by unbolting the clutch from the old compressor and bolting it onto the new one. (This requires a special clutch holding tool available at auto parts stores.)

Drain the refrigerant oil from the old compressor through the suction fitting into a graduated container and measure the amount. Subtract the amount of oil from 4-1/3 ounces to calculate the amount of oil you must add to the new compressor. Add the resulting amount to the compressor through the fill hole.

Mount the new compressor onto its bracket and tighten the mounting bolts.

Connect all lines and electrical connectors to the new compressor. Use new O-rings where the line fittings connect to the compressor.

Re-connect all parts and components that were disconnected to access the compressor.

Have the air conditioning system evacuated, recharged and leak tested by the technician that discharged the system.

Items you will need

  • Socket wrench

  • Jack

  • Jack stands

  • Wheel chocks

  • Screwdrivers

  • Rubber plugs

  • Refrigerant oil

  • Air conditioning compressor

  • Compressor clutch holding tool (if necessary)

  • O-rings

 How Do I Install an A/C Compressor in a Jeep Cherokee?


Take your Jeep Cherokee into a professional A/C shop to have the refrigerant drained before attempting this repair. Never drain the system yourself. Once drained, the compressor hoses may be safely disconnected.

Disconnect the negative battery cable with a box wrench. Disconnect the compressor clutch electrical connection at the compressor by pulling apart the two sides.

Remove the compressor drive belt. Start by loosening the compressor pivot and adjustment bolts with a wrench. Pry the compressor away from the engine with a pry bar if necessary. Remove the belt from the compressor drive wheel.


Disconnect the high- and low-pressure refrigerant hoses from the compressor with two wrenches to keep the hoses from twisting.

Use electrical tape and plastic bags to close off the ends of the hoses and prevent contaminants from getting inside them.

Remove the compressor's attachment bolts with a wrench and remove it from the engine.


Bolt the new compressor in place with a wrench. The new unit will come with instructions on how to drain excess refrigerant oil before installing it. Replace all of the O-rings according to the instructions, lubricating them first with refrigerant oil.

Reattach the drive belt and measure the belt tension with the belt tension gauge before tightening the attachment bolts with the wrench. Belt spans of between 7 and 11 inches should have 1/4 inch of play, and spans of 12 to 16 inches should have 1/2 inch of play.

Reconnect the high- and low-pressure hoses to the compressor after removing the plastic bags and electrical tape. Use two open-end wrenches to prevent the hoses from twisting when tightened. Re-connect the compressor clutch electrical connector and reattach the negative battery cable with the wrench.

Take the vehicle back to the air conditioning shop and have them evacuate and recharge the refrigerant and test for leaks.

Items you will need

  • Wrench set

  • Screwdriver set

  • Pry bar

  • Electrical tape

  • Belt tension gauge

 How to Install an A/C Compressor on a 2001 Hyundai Accent

Recover the refrigerant. Raise the hood of the car and install a recovery system to capture the R134-A refrigerant in your Hyundai Accent's air conditioning system. Install both the low-pressure and high-pressure hoses from the machine onto the car service ports and pump the refrigerant from the car into the capture drum. Once the recovery cycle is complete, remove the hoses.

Raise the front of the car with a jack and place jack stands under the lower control arms where they attach to the front frame rails. Lower the car onto the stands and make sure the car is secure on the stands. From underneath the car, loosen the belt tensioner and remove the dedicated belt that drives the air conditioner compressor.

Remove the old compressor. Use a 3/8-inch socket to remove the back bolt that attaches the suction and discharge hoses to the compressor. Inspect the aluminum flange that is part of the hose assembly for the old refrigerant seal and remove it if it is stuck there. Unplug the wire connector that operates the compressor clutch. Remove the four bolts that secure the compressor to the engine block with the socket. Lower the compressor and work it out from underneath the car.

Prepare the new compressor for installation. Add new refrigerant oil to the compressor. Drain the old compressor by inverting it and allowing the oil to drip into a drain pan. Estimate the amount of drained oil and add that amount plus one ounce. The reason the added amount is used is because some oil will be in the refrigerant that was captured, and some oil will remain inside the compressor. Use only new oil from a closed container as refrigerant oil absorbs moisture which will harm refrigeration systems.

Install the new compressor. Work the compressor into place and hand-tighten all four bolts before securing them with the socket. The bolt alignment is very precise, and tightening one bolt, before the others are installed, will create alignment problems. Once in place, tighten the bolts in a criss-cross manner. Install the rear hose assembly with a new gasket in place. Plug in the compressor clutch connector and reinstall the belt.

Evacuate the system. Install air conditioner gauges to the high and low ports on the hoses and attach the center hose from the gauges to a vacuum pump. Allow the pump to run for a minimum of 30 minutes then close the gauge valves. Note the blue gauge and verify that it is reading in the vacuum zone and remaining steady. If it begins to rise, there is a leak, and atmospheric pressure is rushing into the air conditioning system. If there is a leak, repair it before proceeding.

Charge the system with refrigerant. The Accent uses close to 600 grams of refrigerant or roughly two small cans of R-134A refrigerant. Remove the center hose from the vacuum pump and connect it to a can tap. Pierce the can with the tap and open the blue valve--the suction side--of the manifold gauge. Allow the first can to completely drain into the system. Close the blue valve, attach the second can, pierce the can with the tap and open the valve. Drain the can into the system, start the car and turn on the air conditioner to its maximum setting. Allow the blue gauge to stabilize at 35 to 40 PSI, close the valve and remove the hoses from the car.

Items you will need

  • Refrigerant recovery system

  • Jack

  • Jack stands

  • 3/8-inch socket set

  • Manifold gauges

  • Compressor oil

  • Drain pan

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