LQ4 Swap A/C Question

[RotaryRocketeer]

Truck came equipped with A/C from the factory. Can I just retrofit the LQ4 compressor to my existing system and expect it to work like normal? I admittedly don't know much about air conditioning systems, refrigerant, etc...

[Rich84]

I'm watching this one...Doing the same thing. Have the engine positioned to put the compressor in the LQ4 stock location.

[hatzie]

The LQ4 likely has a variable displacement AC compressor. That unit expects the AC controls from the donor and the electronic AC airbox setup from the donor. You have cables and 14.5volts from the control head in the dash out to the LPCO(Low-Pressure Cutoff) switch on the Accumulator and on to the AC compressor clutch.

I'd get a Sanden compressor and LS adapter brackets from Vintage Air or the like.

You'll also need to build some custom hoses or have someone else make em that will mate the Sanden to your stock Evaporator and Condenser.

I would highly recommend adding a HPCO (High-Pressure Cutoff) Switch on the compressor and wiring it in series between the LPCO on the accumulator and the compressor clutch.

A Nice-to-Have would be a Wide Open Throttle Cutout switch to kill the AC when you kick it down past 2/3-7/8 throttle. From roughly 2002 the LQ4 is a fly by wire engine so you'd need an AC throttle cutoff output from the PCM (if one exists) to a control relay or some such or a mechanical linkage at the go pedal.

[Rich84]

I read on another post somewhere that the van compressors are not variable. If that's the case, is it do-able?

[andyh1956]

AC fittings can be found at Aeroquip that you can make up at home without having to crimp hoses.
We used these in Afghanistan & are slick as Owl %@#!
https://www.bing.com/images/search?v...x=0&ajaxhist=0

[Nodnarb76]

I ended up using a Saden compressor with Dirty Dingo brackets. Fits and works great. had some ac lines made and works like a charm.

[4x4k30]

i used a sanden compressor on my 77 with a 6.0 I used kwik performance brackets and had to get new hoses made and I used r134 in then whole system. I also have a 79 with factory air and used the r134 in it also with no problems .

[RotaryRocketeer]

Thanks, all, for the answers. Looks like the Sanden top mount is the way to go. Good to know that the system can take 134 as well.

[hatzie]

The condenser on these pickups is MASSIVE.
You can get away with R134a using the stock 1980's Harrison R4 radial compressor on these rigs. The old 1970's Harrison A6 will literally freeze you out of the cab on Max AC using R134a.

Make sure you flush out the old mineral or PAG or whatever oil from inside all of the hard parts. Mineral oil is not compatible with R134a so it won't properly travel around the system like Ester refrigerant oil and it'll insulate the inside of the evaporator and condenser. PAG and Ester oil is compatible with R134a but you don't know how much of it there is and how much water it's picked up. Get rid of all of it.
Dump the unknown pedigree oil charge that comes in your compressor and re-fill with your choice of oil. It's likely loaded with humidity and even a hard vac won't boil that much water out. The other benefit is the whole system oil charge comes from a known pedigree source and you know exactly how much oil is in there.
Be very careful to only use just enough oil. Too much oil will insulate the system just like extra mineral oil from the old R12 charge.

[hatzie]

Originally Posted by Rich84

I read on another post somewhere that the van compressors are not variable. If that's the case, is it do-able?

If it's a regular compressor then use it.

[RotaryRocketeer]

Originally Posted by hatzie

The condenser on these pickups is MASSIVE.
You can get away with R134a using the stock 1980's Harrison R4 radial compressor on these rigs. The old 1970's Harrison A6 will literally freeze you out of the cab on Max AC using R134a.

Make sure you flush out the old mineral or PAG or whatever oil from inside all of the hard parts. Mineral oil is not compatible with R134a so it won't properly travel around the system like Ester refrigerant oil and it'll insulate the inside of the evaporator and condenser. PAG and Ester oil is compatible with R134a but you don't know how much of it there is and how much water it's picked up. Get rid of all of it.
Dump the unknown pedigree oil charge that comes in your compressor and re-fill with your choice of oil. It's likely loaded with humidity and even a hard vac won't boil that much water out. The other benefit is the whole system oil charge comes from a known pedigree source and you know exactly how much oil is in there.
Be very careful to only use just enough oil. Too much oil will insulate the system just like extra mineral oil from the old R12 charge.

Great info here. Thank you very much. It'll be nice to have air conditioning AND a 6.0 in this sucker.

[hatzie]

One nice thing about the Vintage Air systems is the smaller footprint in the engine bay. That big ole Harrison AC Airbox that protrudes 1/3 of the way along the engine goes away because it all fits inside the cab.

You will pay a fair price for the nice compact size tho...