dB Zac

Instead of bypassing the original wiring all together, couldnt you hook up the Dark Blue wire to 85, the Brown to 87, blue with a white stripe to 86 and ground 30. That way, your compressor still runs off the orginal fuse, low pressure switch and wiring, just without the cycling switch.

better yet, do what I am going to do and run this adjustable cycling switch in place of the original using that wiring states above

97catintenn

I've thought about using that but where are you going to mount the adjustment ****? in the glove box/

TJE

I used one of those adjustable cycling switches....would go no lower than 60* Not cold enough.

dB Zac

Where did you mount the probe? . I plan on mounting the adjustment **** in the engine bay. It only needs to be adjusted once.

Jim Lane

Running your blower on Low speed will make your evaporator more prone to icing than on Med or High and actually give you colder register temperatures.

You want airflow.

Jim Lane

The probe needs to be inserted between the fins of the evaporator and not the well on the suction line, the calibration would be different.

Do not mount it where continued movement would be likely, you could damage the gas filled tube.

Jim

dB Zac

I know, that's why I asked

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Jschlachta

where is the compressor cycling switch located. I thought the low pressure switch in on h-valve? I see Napa has cycling switches for 134a and for r12 any idea what the difference would be?

dB Zac

The low pressure switch is a cycling switch I guess but in our systems it is a safety to prevent the compressor running dry. When converting to R134, it is common practice to Chang this switch out for a high pressure switch since R134 can run at vary high pressure. Our cycling switch is a temp prob that mounts on the line right at the evap flange



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93-12Smoke

So by doing Jim's mod does it not even use the probe anymore?

93-12Smoke

Also in the picture of the relay it looks like to wires come off the 85 but the hand drawn diagram doesn't show this. Am I seeing that correctly?

gadget.35-06

Some Lennox packaged heat pumps used an SPDT switch similar in appearance. It was designed to switch from heat-pump mode to strip-heat mode when outdoor temperatures made pumped heat unfeasible. The dial could be adjusted from about +20F to around +60F if I recall correctly. I used it on my 91.5 for about two years before the SD709 toy compressor seized. The suction hose wore through on an edge of the fender skirt and contaminants that meandered in before I could fix it locked it solid.

Blowndodge

Well I just jumped the blue/white and brown wire together today. Going to be warm today. I hope this works!!? After all what could go wrong there is only 3 wires!!

Blowndodge

Jumping the blue/white and bround worked fine. The air is really cold now.

But, there's always a but, after about 30 minutes the air starts to warm up some. Is this a function of the evaporator freezing up or something else.

It's always like this. super cold then gradually warming up in 30 minutes... any suggestions?

kcabbie

Jim, I just did the a/c blower modification and it works awesome! I would like to go a head and do this. My truck is a '93. I understand I can just jump the 2 outside wires on the plug. Is this good enough, or do you suggest doing it the way your diagram shows using a relay?

Thanks for all your awesome posts. Got my truck about 2 months back and every time I change something it makes me like it more and more.


Thanks