Air Conditioning Question

[itzbinnice]

Did a search but unable to find an answer to my specific question.

Just returned from the repair shop and had my AC fixed on my 95 Explorer. The compressor was not coming on and they determined it was a defective AC switch that is located under the hood on the passenger side, and taps into a black cylinder cannister. Total cost was 82.00, reasonable I thought considering what parts cost these days.

Now my question, when exactly should this compressor be coming on.
I noticed this past winter in the Northeast as soon as I turned the car on the compressor was coming on with the heat controls. If I moved the control knob to anything but feet, the compressor was on, only in the feet position would it stop. I can understand it coming on with either of the two defrost modes, but not feet and face mode also. I didn't think much about it until now when it stopped working completely.

Today it's about 75, as soon as I came home from the repair I checked it out.
The compressor comes on in heat mode in all settings but feet.
Is this the way it's supposed to work?

I am thinking perhaps something else is wrong and caused the AC switch to burn out, I don't want this to happen to my new part.
Any suggestions or advice are sincerely appreciated.

 

[Glacier991]

the pressure switch they replaced has nothing to do with the internal contols. It switches based on system pressure. The two are unrelated.

 

[itzbinnice]

Glacier991,
Thanks for the info, I feel better knowing my new part won't get damaged.

Can anyone who owns a 95X see if there compressor comes on in the heat modes I outlined in my original post. I just find this is putting an extra burden on the compressor, when in my opinion should not be cycling on in heat modes. I may have other issues here.

 

[mabulok]

On my 2000 the ac comes on when switched to face/feet, it does not operate when in face only or feet only mode. Also, the a/c compressor will run when in these modes whenever the outside temperature is approximately 50 deg F or higher. This is by design. I'm not sure if your 95 is designed this way too, but from what you've described, it sounds like it is operating normally. So, if you don't want the compressor to run, switch the vents to face, or feet. Any other settings will cause the compressor to cycle.

 

[itzbinnice]

Mabulok,
Many thanks for taking the time to reply. I just went out and ran it through all the cycles, it responds identically to your system. My mind is at ease now.

However, I do wonder if the switch replacement was really necessary, perhaps after 9 years of normal use the freon level dropped a bit, and prevented the compressor from coming on. I'll never know at this point. I'm sorry to say it's difficult to find an honest mechanic, it’s like finding a devoted and faithful bride. I did go to a shop that specializes in AC repair but had no prior experience with them. What makes me a bit suspicious is when I asked him by replacing the switch, did the existing freon leak out. He replied no, switch replacement does not let the freon leak out, then he went on to say he topped the freon off.
His eye contact with me stopped when he gave the answer so I was less than convinced this was the truth. The system functions no better or worse from what it did before the malfunction.

I really shouldn't complain, $82.00 is not a great sum for having my AC again.

 

[Glacier991]

That low pressure cutout only operates, if working, at around 27PSI. For it to be preventing a system from coming on would mean the system has virtually lost all its charge. That didn't sound like your situation. So the switch could have been bad. It is on a schrader valve, so removing it to replace it will not cause loss of refrigerant. It is not uncommon to top up a 134 system while you have it in for service. In other words, I think the shop did you right. HTH.

 

[itzbinnice]

Glacier991 (Chris)

Thank you for the words from a pro.
I now believe the guy did the right thing and I will bring him future business.

Trust and honesty are very important to me, if you lie to me once, I won't be back.