Hello guys I need some help. It would be to long to go into my a/c problem, and I really don't want to think about the money I've already spent on trying to get it they it used to be before I switched to 134.

My ? is... is there a way I can wire the cycling switch to a toggle or another type of switch in the cab to where I can cycle the compressor off when it starts to freeze up. I don't want to shut the blower off.

TIA, Tony

 

Sure you can bypass the cycling/pressure switch and wire it too a toggle on the dash. Just run one wire to one side of the connector, then through the switch back to the other side of the connector. This will complete the circuit.

When you do this you will bypass the power to the compressor and if you don't have the switch turned "on" when you press the dash A/C option, the compressor will not turn on and start working.

Not the best solution to your problem but will still work.

 

Well since I know nothing when it comes to electrical stuff I figured I'd better ask. I have spent close to $2000.00 on my a/c and it still does not cool the way it did with r12. It simply will not get as cool as it did before. I've tried slowly moving the cycling switch out to let it cycle longer and it is either blowing 60' degree air or 15' degree air. So the only thing I know to do because I don't want to spend any more money on the thing is to try my idea.
I have thought of maybe even a switch with a thermostat on it that I could control. We'll see.

Thanks, Tony

 

Ouch.....$2000 so far on your A/C....

I'm going to be retro-ing the system in my 84 crew here very soon. Just waiting on a few more parts before I do. I'm totally redoing the system under the hood, no original pieces other then the stuff under the dash. I did this with my 68 Town and Country wagon and it works great.

I shouldn't be into the whole new system, even with the cost of charging the system, for more then $500.

I'll be writing up a step by step thread to give another option for guys redoing A/C systems in there 1st gen's.

 

Tony,
Last week here in Southern California it started to warm up enough to use my air conditioner so I cranked up the A/C to MAX and then within minuets I was feeling this:



It is real simple to bypass your cycling switch and control it manually, mine has not cycled since August 08, 2006 and my evaporator has only iced up no more that probably a dozen times and they were my fault because the blower was down too low but switching to vent for a minuet or so had it thawed out and working again.

Where you live and the humidity of the air is also going to have influence on evaporator icing, the main thing you need is maximum airflow on both the evaporator and condenser.
If it has been converted to R-134 an axillary condenser fan is a must, stop and go driving can cause the head pressures to stall the compressor.

https://www.dieseltruckresource.com/...h-t112028.html

When we go on long road trips the family usually complain about how cold it is in the cab so they are always wearing a coat in the truck. I am going to install an adjustable thermostatic switch in-line with the relay coil so I can control the evaporator temperature so it doesn't get so cold when they are in the truck.

I have worked in HVAC for many many years and used to do a lot of automotive back in the days when a can of genuine R-12 cost .69 CENTS.

I am going to use a thermostatic switch like this one:

http://www.napaonline.com/Search/Det...517_0120135380

and mount it where I can conveniently adjust the ****, the end of the capillary tube has to be inserted between the fins of the evaporator.

Before I bought one from an auto Parts I would browse around a Pick-Ur-Part and look for some of the old under dash units also check Truck Salvage Yards for the old Kysor or similar roof air conditioners, they all had them.

Now that I think about it you could also use one salvaged from a discarded window air conditioner as long as it has a dial that clicks and you can see the probe stuck between the fins in the front, I am pretty sure these would work

Just in case you did not know, DO NOT cut the long probe on these switches, it is actually a small cap tube and it is pressurized with freon.

By installing one of these you will be reverting the cold controls back to the 1960's technology when they actually worked.

Jim

 

Thanks Jim that is some good information. Yes one of the problems here is the humidity, it is 73' here this morning but the humidity is brutal already. I did try in the past doing your write up on the a/c cycling switch but again the humidity makes it in efficient.

Thanks, Again