QuestionQUESTION: 1999 Nissan Frontier 4x4 V-6 I replaced the Expansion valve because the air conditioner would blow cold when the outside temp was low, however, as the outside would rise the air conditioner conpressor would kick out and it would blow hot air. This would repaet from cold to hot to cold to hot on hot days of 80 to 90 deg.
I don't want to replace anymore parts and i cannot afford to pay a local mechanic $140.00 per hour to locate the problem. I do not believe the AC Condenser Fan is running at any time. I think that may be the reason the pressure is rising and tha compressor cutting off on hot days. I would like to know if there is a way I can torubleshoot the fan to determine if it is working and also the Trinary Switch which also controls the fan, maybe that way I can find what I need to replace.
Thanks for your help
ANSWER: Hi Charles -
The fan is supposed to kick on as soon as the A/C goes on.
Than being said, you can troubleshoot the system by getting a 12V probe type light tester. Purchase it at any auto parts store for a few dollars. Ground one side, and while the A/C is on, engine running, check the leads going into the fan. Ensure you contact bare wire. One of the leads should have power. If so, then replace the fan motor. If there is no power, check the power at the switch, both power going in and power going out. If there is power going in, but not out with the A/C on, then replace the switch.
Hope this helps -
aloha
calvin
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QUESTION: I have power going to the fan and it is now running. However, the compressor cuts off when the outside temp get hot or when I slow dow to city driving speed. Compressor cuts back on and it cools as soon as I speed back up. I have replaced the expansion valve, head pressure is good and gas is good. Could the trinary switch be bad and shut the compressor off although it makes the fan run. I understand the trinary swith serves to make the fan run as well as control the compressor in high or low pressure.
ANSWER: Yes, Charles. Your knowledge and assumption is right on.
Assuming that the head pressures are correct (Have you checked it with a manifold?), you can check the switch the same way you checked the fan with the probe. If the power cuts out after the switch with the same head pressure, then replace the switch.
Thanks for the rating. I appreciate it.
calvin
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Switch
QUESTION: Hello again Calvin. In refrence to my last reply when I said I have power going to the fan and it is now running, that was only temporary. I believe you said it should run when the air is truned on. Well, sometimes it does and then again it doesn't. Although, I have power coming out of the Trinary switch as it starts toward the fan, I have found another something between the Trinary Switch and fan. It is a little something that is about as big as mu thumb nail and about an 1/8 thick that has a plug on the back of it. Wires come from the Trinary switch to this and from this to the fan. I am wondering if this is some kind of thermostat thet measures the temp of the air going into the condenser. This, whatever, it is is mounted about 2 inches away fron the condenser, righ in the middle in front. Make me wonder if this, whatever, it is is responsible for turning the fan on at a certain temp. Also makes me wonder if I could remove it and let the wires go directly from the Trinary Switch to the fan as this might be the culprit. You are the expert, I am sure you know what this little thing is and what function it plays. I will post a photo of itit will be below the white bracket on right and horn on left and connects to nothing except the wires between the Trinary Switch and Fan connection.
thanks again.
AnswerHi Charles -
Can you tell me - while the A/C is on, and fan NOT running, do you have power between this sensor and the fan?
You are correct. That device senses temp and higher heat will send a signal to the fan.
Let me know -
aloha
calvin
