I don't have a diagram, but here's what I did.

I already had my trinary switch and pcm paralleled to my fan relay coil so either could ground it out.

I cut loose my pcm fan control wire and connected it to one side of the micro relay coil.

I took 12v power from my fan relay coil (86) and connected it to the other side of the micro relay coil.

I took the fan relay coil wire (85) that the pcm was tied to and connected it to the NO (normally open) contact on the micro relay.

I took the common of the micro relay and grounded it to chassis ground.

Basically the pcm will ground the micro relay to turn it on and ground the fan relay which is also controlled by the trinary switch ground.

 

Wouldn't it have been easier to just turn off the error reporting to the fan DTC you were getting? I get that same code in my '33, but dont have a CEL so I didnt mess with it, but was planning on doing it on my current project.

 

That would be much easier, but we don't have access to HP tuners so it would have cost us much more then a $2.00 relay.

 

Ah, gotcha, that makes sense. I was just making sure I wasnt missing something since I was planning on doing my current project that way.

 

Looking into a Vintage system, my problem at the moment is I have a smoothed firewall. I know that they sell mockup kits for prefitment which looks like I will need to weld studs to hang the unit from, i don't have a problem with that as the fire wall is all that is left before paint. My question, are there any other options I can explore as to weld studs with out purchasing the mockup unit? The vehicle is a 64 Chevelle that will have a 6.0L swap.

 

I used a Classic Auto Air system Mike - I think these guys used to work for Vintage. I have a center console that extends to the top of the tranny hump (82 Volvo) - so I was able to mount the unit on top of the hump without making any firewall penetrations. Except for the hoses of course. Is there any way you can hang the unit from above on the 64 Chevelle?

 

Not sure this was a non ac car to begin with, and not sure how it mounts, meaning new unit.

 

My replacement unit was a universal device -- so it all had to be fabricated to this car. Are you planning a V.A. system that's designed for the '64 or a universal unit?

 

Per the VA magazine it's for the 64 65 Chevelle

 

Well - their approach to mounting will dictate yours -- unless of course you want to fabricate something different. I've installed a number of aftermarket A/C units in various types of cars over the years. I've never mounted anything through the firewall, for what it's worth. So if you want to avoid that it's possible - but fab will be needed.

 

Thanks for the replies, not aposed to fab something up. Will likely have to bite the bullet and seek out the mock up unit, same ole story, budget is suffering, working on getting paint done.

 

I remember it well - death by a limited budget and a thousand details...hang in there.

 

Ive always just used the actual unit for mock up purposes. On my current project I bought the sure fit one but didnt like the way it looked when mounted so I modified the mount and moved the unit to better suit my needs. I think though, that if you buy the mock up unot they will credit the cost when you by an actual kit if you send it back. Might be worth looking into.

 

Me too - the dimensional info they provide has always been good enough that I can determine which unit will fit. Once I've confirmed that, it's just a matter of figuring out how/where (precisely) I want to mount it once I have the actual unit in my hands.

 

I think that it is a dealer option on giving credit on unit from a mock up unit, probably my best option. Looks like a trip to St. Louis is in order, thanks for the help.

 

As stated this is a loaded question. The first thing I would ask is:
1. Do I have a factory ac car and everything that goes with it?
2. Do I want a smooth firewall?

If you answer no then I think that an aftermarket system is pretty much your only choice. I have had both in my car and actually went from a VA to a factory unit. My 2 biggest gripes were that the fan was noisy and that the system is 100% recirc. I personally only use the recirc button to do an initial cool down of the car if it is extremely hot then it is fresh air all the way. I also have a vent switch that does just that with the factory unit. As far as blowing cold both work well but I personally think the fresh air helps put positive pressure in the cabin and helps push out the hot air.

For those of you splicing into the fan circuit I question the practice other than having no access to a tuner. If you are using an older 24x pcm then all of them can be made to work properly with a VA unit along with electric fans. If you are using dual fans then the proper way to do it would be to add a pressure sensor inline with the unit. This will give you 2 speed or second fan control with the ac. If you don't want to then you can still just run an ac request and the initial fan with turn on with the ac request automatically just like your splice option but you get the added benefit of idle control when the ac is on. I think this should be enough to keep the unit running on even the hottest days because the second or high fan will still work with the coolant temp switch. You would still need a tuner to get the system to work properly regardless of the OS you are using for any 24x unit if you want to wire everything through the pcm. If your running a stockish motor then this may not be such a big deal but if you start modifying with a cam, header, etc it will affect your idle and you will need to tune it anyway. Factory variables need to have the pressure sensor tuned out if you are not using one and most of the factory OS's with a fixed compressor need to have the fans turned on unless you are using a regular fan but most of those go away after 05-06.

For cost there is a guy on the S10 forums and 240SX forums that will set you up with a tune/swap OS's, etc that will work properly for $50 or less. While he is at it he can tune out any other DTC's etc as needed until you are satisfied. This seems more than reasonable to get a system working exactly like you want without breaking the bank.

 

This part is not quite that straightforward. Some OS's don't support the direct AC request. LS1Nova can add a more indepth response than mine...

 

My vintage works very well in my Camaro, but the AC request wire coming from my PSI engine harness did not raise the idle like I thought it would and I have issues with the car wanting to stall when the compressor kicks on. It gets better as the car warms up but there is still a noticeable dip in idle. A bunch of the guys here tried to help me but I got confused and have just been living with that issue. If the idle becomes a problem these guys can certainly help you figure it out.

 

agreed, It would not work for ours.

 

If you raise the base idle, up from 525 to 550-575, that should eliminate the problem for you.