In most cases, the relay is mounted on the fender well or fire wall. The relay in a typical A/C control installation has a three-wire connection. One wire is a ground, one wire is the input from the interior control panel and switches, and one wire is the power feed to the A/C compressor clutch.
The relay in your car or light truck’s air conditioning system controls the compressor. By using a relay, the high-current electromagnetic compressor clutch can be controlled by a low-current switch.
You can use your car’s owner’s manual to help locate the fuse. If the new fuse blows once it’s been replaced there is a short in the system. This relay supplies main power to the compressor via the system fuse. Locate the relay in the fuse panel or power distribution center using the owners manual.
AC Relay Replacement Cost
Replacing a relay costs $80 to $300.
What is an AC fuse? The fuse is a wire inside a glass casing, found in the disconnection box connected to your AC. The fuse is a protective measure meant to protect your air conditioner from electrical damage.
The most common problems that cause a lack of airflow include frozen coils, broken fan and restricted airflow due to dirty air filters or vent obstruction. However, there are many other issues that can lead to minimal airflow, so it may be necessary to ask the professionals.
Test the load: If you saw a voltage reading during the previous step, run the same test on the “load” side of the fuses. You should again see a reading between 220 and 240. If you see a voltage reading on the “line” side but not the “load” side, it means you have a blown fuse.
First of all, your electrical system might be having problems. … While this prevents serious trouble such as electrical fires, it also means that a single blown fuse can cause the entire air conditioner to stop working.
Try cleaning your air conditioner’s filter and the coils to see if improving the airflow fixes the problem. If there is ice buildup, you’ll need to run the unit with just the fan in order to melt it off. If that doesn’t get the unit blowing cold air again, it could be refrigerant levels are low (see below).
An air conditioner uses relays to switch the system’s high-voltage parts on and off. The relay contains a low-voltage coil and a high-voltage switch, sometimes called “contact points.” When the thermostat switches on, a low-voltage signal energizes the appropriate relay.
You’ll need to remove the metal connecter attaching it to the relay system first and then use pliers to strip some of the wire (no more than ¼ inch) on either side. Using electrical tape, connect both ends of the wire back to the relay housing so it completely bypasses the missing relay and closes the circuit.
You can buy a relay for as low as $5 for a generic multi-purpose relay or as much as $350 for a complex, direct-fit relay. A starter relay costs around $20 to $80 while a main relay costs around $20 to $200.
A faulty relay often produces an audible clicking sound when you turn your car. Contact a mechanic immediately if your car fails to start and you notice this sound.
An AC’s reset button is typically red and visible, so it should be easy to spot. If you don’t see a reset button on the outside, it could be located inside the unit behind the service panel. Before poking around inside the machinery, be sure to cut power to the system by flipping off your circuit breaker.
Because of the volume of air that is moved by the blower fan, the motor may pull up to 20 amps or more at high speed. To protect the blower motor power circuit, a 20-, 25- or 30-amp fuse is usually located in the fuse panel under the dash.
At the compressor’s front side, unplug the single wire connector, take a jumper wire and attach it to the wire that you just disconnected from the compressor. Connect the other end of the jumper’s wire to the positive terminal of the car battery. This will enable the compressor to start manually.
Car makers use an electro-magnetic clutch to engage and disengage the air conditioning compressor. When power energizes the clutch coil, the magnetic field pulls the clutch in to engage the compressor shaft. If the clutch doesn’t engage, the air conditioning compressor can’t pump refrigerant.
If the compressor isn’t starting, check the wiring connecting the two units. If it’s a blown fuse or tripped circuit breaker, the search has come to an end. Other potential causes may include a faulty thermostat, mismatched indoor and outdoor units, or the AC may just be old.
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