If the original trinary switch terminals are different, a four wire … This protects the compressor from damage. endobj Verify ohm meter operation. Insert a jumper wire into the two openings of the plug. Remove the air conditioning pressure sensor and test the electrical connection leading to the sensor from your vehicle's electrical harness. To submit your questions or ideas, or to simply learn more about It Still Works, contact us. Make sure you’re measuring single ohms, and not mega-ohms. On the side of the switch it used to say "R12 R134a." I added about an ounce of oil. >> If it is not functioning, then the system can not operate, and will be unable to produce cold air. Any sensor codes that come up on the OBD II scanner can either be read directly off of the scanner or you can look up the code on a website such as OBD II Code or AutoZone. I have a 1992 Rexhall airex motorhome built on a Ford F53 chassis with a 7.5 litre (460 cid) V8 engine. And the electric fans spliced into it. The best way to find the pressure switch in your air conditioner is by consulting the manual for your car or in-home air conditioning system. Ha! Then when the engine temperature gets warm enough the Engine Temperature Switch or Thermostat will close and keep the Cooling Fan on even if the Air Conditioner is turned off. Listing both refrigerants makes me think the switch could work with either system. Locate the evaporator, which is a block or grille-type component connected via hoses and tubes from the compressor, which has a belt and pulley system. Also, it has two sets of contacts, possibly one set to use for R12, and the other for 134a. One might wonder how to jump 3 wire ac pressure switch by own. Disconnect the pressure switch electrical plug. I'm getting a little confused with the Trinary Switch. If you have found the terminals, get your leads and touch one on each terminal. Shown below are the terminal positions, typical wiring colors, and usage. The fan appears to have been re-wired to a switch on the dash. 1) is low pressure cut out that shuts off the compressor when the system is low. Must have used disappearing ink! I had no way to verify the reliability of this information. Another type of damage that is common in multimeters is normal wear and tear, which leads to cracks and broken components. Also below is the internal schematic for each of these switches. The pressure switch, found on the same line as the service valve, has a set of low voltage wires connected to a plug. You’ll know once they’re broken, as they will cause the whole air conditioner system to act out. All you need to do is wire the trinary switch output to the fan relay(s) for full speed. Although there are different types of pressure switches, they all work the same in principle, and testing them with your digital multimeter will look the same. Locate the A/C, and find the pressure switch attached to it. If the pressure is at an adequate level, then your pressure sensor may be failing. Maybe somebody could post it or a link. Put the multimeter in the Ohms position (usually displayed with the Ω symbol). This gives you the initial test results. Select the ohm meter function. Then set it aside. At the core, a pressure switch is the same as any other switch. At some point it was retrofitted from R12 to 134a. Required fields are marked *. Let us find the reasons behind bad AC and the repairing process. So there seems to be a problem somewhere, with the low side reading too high....fully charged, but no cooling. Four Seasons’ trinary switch part numbers are 35889 and 35901. This not only signals the need for a recharge of refrigerant, but also saves the compressor from running without the proper lubrication. In most models, you will be able to remove the switch separately from the A/C itself, so you don’t have to take out the whole A/C. %PDF-1.4 I seam to have a problem with the site, so not sure this will be readable. High pressure side would rise to 250, and then the fan would kick in, as it should. This article was written by the It Still Works team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. Or does it kick the compressor off when a set high pressure is reached? It preforms 3 functions. Turn on the multimeter. This page was generated at 1 minute ago. /Creator (��%����qd2Z%v��\\��c��J�&) If the A/C system is below 50 psi with the compressor not running, Then you are low on refrigerant and that switch is doing its job and keeping the compressor from running and burning it up. Please enable Cookies and reload the page. Is there a way to test it without a fully pressurized system? I was expecting it to read 25-35. Oh..so you didnt need to test the pressure switch, you need to test the compressor clutch. One might wonder how to jump 3 wire ac pressure switch by own. If not, repair the leak and add refrigerant. You might have to do some repairs by yourself to make it run correctly again. Put one of your leads on the common terminal, and the other on the normally open terminal. One controls the compressor clutch, and one controls cooling fan for the condenser. When you turn the pressure switch around, you’ll notice a side with different terminals. I've had it for a year and a half, and this year I am trying to get the AC to work. The pressure switch can be mounted to A/C pressure line, compressor or accumulator/drier. If the compressor does not turn on, check the compressor relay. Ć`VF�z��� u������CUAC{\C ��i����B�dv�,Z �h�^��Z�-� Set the resistance range to 'x1.' The compressor is what pumps refrigerant through the entire system. Check the pressure of the air conditioning system by attaching a low pressure gauge from a refrigerant recharge kit to the low pressure fitting, located between the accumulator and the compressor and marked with a capital "L." According to AA1 Car, on an 80 degree day, the low pressure gauge should measure 56 psi (pounds per square inch) or higher. I don't know about amount, without a sticker, try and contact the Mfg, otherwise its going to be trial and error. Part 2 of 3: Remove the A/C pressure switch. Knowing how to test a pressure switch with a multimeter might save you precious time and money, as it can pinpoint the problem pretty fast. If you don’t see any terminals, there is a chance you need to remove the cover first. M�(�$~ȳ���L�7q_�n�P�ijUf5ɨV5�� �V-?�0��� R���v��Q���΁�ǿ_�S�kRH�I��%���s��$X��+io��ol��Y9K�~�(�x��N,&��Zх]��'I&����.�O�۾b�A� 7���)h`�L�d.�� �Ax�oՔ���������2ӧbG};0��䃚�i�eҮLL��]��)S/����\��]�˹aa��6�i�[�pʽ��w�& e����� ���m\�w�9ƿ�s��"#�j����ԚNs��|#�!H`tO�þ"�����vR�,�~qy���. Locate the OBD II port on your vehicle, which is typically located within a few feet of the steering column. Thank you. Touch the probes of the multimeter to the electrical harness end of the electrical connection and turn the ignition key to the accessories position. 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One opening should read between 12 and 14 volts. >>stream When the fan kicks on, the high side pressure slowly falls. The A/C system has to have at least 30psi in the system for anything to work (compressor protection). I did that to mine while I was replacing all the o-rings in the system. Compressor kicks in as it should. Turn the air conditioning system on. Seemed like all the Ford trucks of this type were anywhere between 2.0lbs and 2.75 lbs. A pressure switch is a small device that you can find around equipment at homes, in cars, vending machines, and industrial manufacturing plants. Remember that actually fixing a pressure switch can be very tricky. I think those are "quick connect" fittings used during mfg so the system can be connected while it (or part of it) is already charged. Air conditioning pressure sensors, also known as AC switches, turn off a car's air conditioning system whenever the refrigerant pressure reaches a lower extreme. Your browser will redirect to your requested content shortly. A closed switch should read 0 Ohms. There are several problems that can arise with pressure switches. When it comes to testing pressure switches, you’ll have a hard time finding a multimeter that won’t perform a pressure switch test. This means that once the component (a pressure switch in this case) is disconnected from the main body (the A/C unit in this case), you can test the pressure switch as you would any switch. If the compressor turns on, replace the pressure switch. Lift the locking tab on the plug before pulling the plug free. But the writing on the retrofit sticker is no longer visible, so I don't know when the retrofit was performed, or the amount of refrigerant the system holds. Is there any way to test this switch off the vehicle? Photos show how to connect the ohm meter to the switch for testing. You can do it the way mentioned above, or you can test it another way. Do they need to be there? That helps. Double check that your leads are in the right place to test for Ohms, and get the switch. Turn the system off. How to test a 4-wire trinary switch for air conditioning system - Answered by a verified Toyota Mechanic We use cookies to give you the best possible experience on our website. AC systems in vehicles run with a pressure switch. Refrigerant does not wear out or evaporate: only leaking air conditioning … Thanks. Most likely, a vehicle with an air conditioning system that will not cool has a low refrigerant level. Much easyer to test on the vehicle with a set of gauges on the A/C system. I would replace with a drier that takes std O ring fittings and eliminate the quick connects. This means that once the component (a pressure switch in this case) is disconnected from the main body (the A/C unit in this case), you can test the pressure switch as you would any switch. Front a/c only, so just the one evaporator. My compressor does not kick in, but I can get it to operate by taking 12 volts directly to the compressor clutch. Check the voltage going to the plug with the multi-meter turned to DC-Volts. This A/C Manifold Gauge Set is designed to test automotive air conditioning systems (using R134A Freon only) by comparing the "high side" and "low side" pressure reading to the vehicle manufacturer’s A/C system specifications. /Length 13356 /Author (��"����|6*A!) If the tubes are not cold to the touch, then there is no refrigerant traveling through them, meaning that your refrigerant is either too low or the pressure sensor is not working correctly. As I mentioned, this 1992 motorhome was retrofitted from R12 to 134a at some point.

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