Almost every single electrical system on a car is powered through some kind of switch or electrical relay, and the AC system and compressor are no exception. The AC compressor relay is responsible for supplying power to the AC compressor and clutch. Without this relay, the AC compressor will not have power and the AC system will not function. The AC compressor relay is no different then other electrical relays - its electrical contacts will eventually wear or burn out, and the relay must be replaced. When the AC compressor relay has failed or is beginning to fail, it will begin to display symptoms that indicate it may be time for it to be replaced. The AC compressor is powered by the relay. If it is not functioning properly, then the AC system will not be able to produce cold air correctly. When a relay is starting to fail, it may give weakened or intermittent power to the compressor, which will result in weakened or intermittent function of the AC. The AC may function fine in one instance, and then shut off, or deliver inconsistent performance in another.

This may be a potential sign that the relay may be going out. One of the most obvious signs that the AC relay may have a problem is that the compressor is not coming on at all. In most cases, when the AC is turned on you will be able to hear the compressor switch on. It will usually produce a familiar clicking noise from the clutch being activated. If when you turn it on you do not hear the clutch being turned on, then perhaps it may not be getting power, due to a failed relay. Another symptom that the AC relay has potentially failed is that there will be no cold air at all from the AC. If the relay fails, the compressor will not operate and the AC system will be unable to produce any cold air at all. While there are several reasons as to why an AC may stop producing cold air, a failed relay can be one of the most common. If you are experiencing issues with your AC system and suspect that your AC relay has either failed or is beginning to fail, we recommend having it diagnosed by a professional technician.

If your AC relay is found to be faulty, they will be able to replace the AC relay if necessary. A  Engine compartment harness B  Engine compartment harness C  Engine compartment harness D  Engine compartment harness E  Engine compartment harness F*  Engine compartment harness RL1  A/C condenser fan relay RL3  Radiator fan relay RL4  A/C compressor clutch relaycar air conditioning repair derby RL5  Rear window defogger relayac unit r22 for sale RL6  Blower motor relaycar air conditioning repair rochester 1    30  A/C condenser fan motor, A/C compressor clutch 2    15  Dash lights, front side lights, front parking lights, license plate light, taillights, taillight relay, trailer light connector (via relay)

3   7.5  Dome light, ignition key light, cargo area light, spotlights 4    20  Radiator fan motor 5    15  Turn signal/hazard relay, turn signal lights 6    15  CKP sensor, CMP sensor A/B, ECM/PCM, IAC valve, injectors, PGM-FI main relays 1 and 2 7    15  Brake lights, brake signal to ABS modulator, cruise actuator, ECM/PCM, horn relay, trailer lighting connector 9    10  Radio, data link connector (OBDII), gauges, immobilizer receiver and indicator, keyless receiver, MCU, XM receiver 10    30  ABS modulator control unit 11    20  Rear defogger 12    40  Blower motor 13    40  Fuses 7, 22 and 23 in under-dash fuse box, power window relay 14    40  Fuses 2, 3 and 15 in under-dash fuse box 15    15  Daytime running lights control unit (Canada), high beam indicator, left headlight 17    15  Daytime running lights control unit (Canada), right headlight

18    30  ABS modulator control unit 19  100  Battery, headlight relay, power distribution 20    50  Ignition switch (BAT)Troubleshooting a Honda Civic AC When Honda Civic air conditioning system (A/C) is being diagnosed it must have Freon in the system. If the system has sprung a leak somewhere and the Freon is gone it is no longer an active system that can be checked. A leak would have to be repaired before further diagnosis can continue. Freon can not be released into the atmosphere and must be reclaimed in a machine and reused. There is a major fine for releasing it into the air. For the purpose of this procedure a circuit tester and a set of air conditioning gauges will be needed. About the A/C System There are several parts to an air conditioning system which makes it somewhat complex. The main parts of the air conditioning system include:Compressor: This raises the pressure and temperature of the Freon.Dryer: This removes sediment and captures and retains moisture.

Condenser: This acts like a radiator and releases the heat to the atmosphere.Accumulator: This does the same as the dryer except it is used to also capture liquid Freon so it does not reach the compressor. Depending on the year, the Honda Civic may have a dryer or an accumulator, but never both.Expansion valve: This takes high pressure Freon and turns it into a low pressure, low temperature spray that moves into the evaporator inside the cabin and withdraws the heat. Since there are so many parts involved, the first thing is to test the system from inside the car and see exactly what is happening so there is an appropriate place to start looking for a problem. If the inside fan does not come on with the A/C, lift the hood with the engine running and the A/C on. Look to see if the compressor is turning and feel the largest A/C hose to see if it is cold. If it is and the compressor is on, the system is all right and the problem is in the blower motor. If the compressor is not on, the problem could be a matter of power to the system, a bad control head on the dash or no Freon.

Start by checking the fuses in the fuse and relay panel under the hood on the drivers side. Replace the fuses as necessary. If fuses were not the problem, hook up the A/C gauges to the system with the red line going to the high side (the small line) and the blue line going to the opposite large diameter low pressure side. The gauge should show close to 80 pounds on the blue low side and 140 on the red high side, depending on outside temperature. This is with the compressor off. It takes this much pressure to turn the low side switch on and allow the compressor to work. At this point the inside fan is a separate issue if the compressor was not on and will be dealt with next. If the pressure on the gauges was less than prescribed there is a leak in the system and it must be repaired to continue under the hood. The fan is under the passenger side dash close to the glove compartment. Use the circuit tester and check for power at the 2-wire connector on the blower motor (the key and fan need to be on).

If there is no power to the fan, the fan is bad. If there is no power, move to the blower motor resister right next to the blower motor. It is usually to the left and slightly to the rear and is used to control the speeds of the fan. Check to see if there is power to the resister. If there is power, the blower motor resister is the problem and should be replaced. This is a very common problem and inexpensive. It can be done without going to a shop. If there was no power it is a bad control head on the dash. If the A/C system has too little or too much Freon, the high or low side valve will shut the system down to prevent damage to the compressor. If this is the case, a very expensive reclaimer must be used to adjust the Freon level. An ASE technician certification and a MACs card is needed to own one so it must go to a shop for further diagnosis. However if there is Freon in the system the following is a good diagnosis of problems that can be identified: If there is a clattering noise under the hood with the A/C running, the compressor is going bad and will soon need replacing.

If there is a metal to metal sound like a grinding when the compressor comes on the clutch is bad on the compressor and can be replaced separately. If the system is not cold enough, feel the large line under the hood for the A/C. If it is warm feel the small line and be careful, if the compressor is working the small line should be hot. If not, the compressor is going bad. If the large line is cool but not cold and the small line is hot the system just needs a recharge. If the compressor keeps cycling on and off frequently the system is low on Freon and only needs a charge. If both lines are warm or hot to the touch, the expansion valve is malfunctioning ad it needs to go to the shop. If the A/C is cold when the car is in motion and warms up when stopped, the condenser fan under the hood is not working. You don't normally give the inner workings of your Honda Civic a second thought until something goes wrong, especially when it affects... Honda air conditioners are designed to efficiently cool or warm the air in the car.

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