Technical Salvage Yard Air Conditioning ? ? ?

Most modern defrosters us the AC to dry the air before blowing it on your windshield. It helps to clear away the fog quicker. It's not absolutely necessary, because many older cars didn't have any AC at all and did just fine. It would be hard to route the AC from the trunk to your heater or your defroster.

I can imagine running the AC from the trunk, up through 2 hollow manifold-tubes on each side of your seats, though. That would be cool, especially in a convertible.

daddio211 beat me to the next thing that might make a trunk mounted AC not cool enough. You would need a return for the cabin air to the evaporator so the AC doesn't have to cool fresh, hot air all the time. It can't keep up with it. If it can recirculate the cabin air, it doesn't have start from scratch all the time. That's why your house's AC has a return-air vent.

 

Does the under dash part of the system have to be oriented a certain way? Tubes horizontal, vertical? The reason I ask is I really have no under dash area in my truck, but do have a narrow tall area behind the seats where I could put small twin heat/cool units. I would be stuck using fans for defrosting the windshield, or maybe a separate electric defroster unit above the windshield.

 

Its in a gas state so it shouldn't make a difference as the pump sucks it up to it

 

on the old international eagle semis they put the heater and a/c under the passenger seat , and made a 1-2" tall flat duct that was the floor of the cab on that side to the dash board to all the vents and defrosters , worked real good as the evap wasn't heated up by the turbo near the firewall .

 

Had a 82 Dodge van I used for my a/c biz. Used r-12. leaked like a sieve and r-12 was way pricey and hotshot had just came on the scene. Pulled the r-12 out what was left and vacuumed out the system. Recharged the system like someone said with a digital meat probe from Wal-mart for like $8.00 in the supply duct.. Kept adding a little at a time and it was blowing damn cold air. As too your question about how do you charge or top off the charge cause it;s a blend it has to be charged as a liquid( Bottle upside down into the lo-side of the system. very important. Hi-side could explode the can and would really mess up your day. Be real careful and get familiar with the difference between the hi-side and low side of the pressure system. I've seen front windshield busted up by a can hooked up to the hi-side. FunnythingI was told by a automotive a/c supply house that if I purchased a r-12 compressor and they knew I ran hotshot through it they wouldn't warranty the compressor. Also was told that there is a molocule of clorine in the mix which shortins the life or rubber hoses. I don't give a shit it was a 82 van with orginal hoses Etc and it was an experiment and I like the way it worked . Had to have my a/c chillin in my work truck. Thats my experience with hot shot. Also if you convert to 134a you really need to go with a bigger condenser to get close to the original Temps you got with the old r-12. yruhot....doug

 

Also you can charge into the hi-side the liquid only on the initial charge when filling the system. once unit is running only charge the liquid into the lo-side very slowly. Just barely cracking the valve on bottle or manifold. Liquid going into the compressor can wipe lots of stuff out in a hurry. Liquid doesn't compress very well. Just a quick thought.yruhot.......Doug

 

I don't think the orientation matters but I'm not sure, so I'll let someone else answer that question.

However, as for the two small areas behind the seat: All you really need are some tubes with a fan blowing on them. You could bend up your own evaporator out of copper tubing to custom fit the area available, if you had to. It wouldn't be as efficient as if it had fins like on a commercially made evaporator but it would get cold. You might also look at a refrigerator's or window AC's evaporator instead just those from cars. They are compact and may be another source of free evaporators for you. The "Freon" doesn't know or care where the evaporator came from.

Wish you guys lived closer to me, this would be a fun project.

 

Orientation only matters when it comes to the drains. If you can get the water out of the coils and on to the ground with out going through the controls or motor, then it won't matter which way you mount it. Under dash units need to be leveled up so the water runs out the lower back drain holes, just like every other A/C unit made. You also want the water to drain away from the vents, or you will get sprayed with a mist as the unit runs.

Joe

 

Thanks guys! Joe H, I hadn't thought about condensation drains, so your thoughts probably saved me some trouble.

 

Guys, what's about controlling engine RPMs when Idling and AC is ON?
I have heared that there is need to open throttle to increasre RPMs on I4 engines because load from AC compressor is enough to stop engine. Is there same problem on V8s ? And are there some complete bolt on solutions for controlling RPMs for carburator engines?

 

Isn't isobutane flammable? A friend of mine had a rusted out OT Cadillac that used R12. He needed to fill the air as it had a slow leak. He used 2 cans of R134 in the R12 system and a can of stop leak and it has worked for 4 years now with no problem.

 

napalmv8, My 62 Impala wagon with the original A/C system has the control your talking about. It might have been necessary with the original 283 but with a late model 350 Vortec engine now installed it is deactivated and no increase in rpm's is needed when the A/C is turned on. The 63 Belair in my avatar has a Vintage Air system with a TPI 355 and theres also no device for increasing rpm's. Its not necessary.

Gary

 

10x for the reply!

 

He probably had enough R-12 in the system that it is helping carry the oil through the system. R-134a does not carry the oil since it is not miscible with mineral oil. Isobutane or propane will carry the mineral oil, and yes are flammable; although a good system is closed and has no oxygen so there is not an explosion hazard unless it leaks out. Many of the R-12 replacements are hydrocarbon mixes of propane and isobutane. The blend is so it mimics the P-T curve of R-12. Propane by itself is closer to R-22 P-T curve.

 

the way the increase the rpms on tpi cars is they put a vacum bleed solenoid on the Tpi base or use the IAC valve to adjust the speed .

 

I answered this yesterday

 

FYI, there is no rpm change on my TPI car. The car has a tach and rpm's stay the same with A/C on or off.

 

If you have any type of computerized fuel injection, the computer is constantly controlling your idle speed. When the compressor clutch engages and puts more load on the engine, the idle speed control adds throttle to compensate.
It you are running a carb, you need the dashpot to physically open the throttle a bit.

 

the computer adjusts the idle a/f mixture 40+ times a second you will not see or feel the difference when the compressor kicks in thats is the nice thing about Fuel injection, it gets better when you have multiport which adjusts 52 times per revolution of the crank , my O/t Fi 4 cylinder car the a/c kicks in and out and the computer keeps it nice and smooth ,

 

Seems like it wouldn't be too hard to build a slotted bracket to hold any small 12V solenoid to move the idle stop up a tad.

Or, instead of slots in the bracket, you could thread the solenoid plunger and adjust it's length with a lock nut.

It could be wired to come on at the same time as the compressor clutch.

 

have to find a solenoid that kicks out when power is applied or set it up with a relay so it will remove power to it so it kicks out ( using a idle kill solenoid which are easy to find and cheaper) you can find the idle kill solienoid brackets on carbed cars of the 70's and some 80's dancing needle carbs . just have to bend the brackets to reposition where it hits . almost all Pontiac v-8s had them after 76 till 81

 

BTW, my friend's 70s cadillac has solenoid which is activated when economy switch on dash is off. If I'm not mistaken, in economy mode engine is idling without some adjustments when AC is off or on. When economy mode is off, solenoid adds some throttle to increase engine and AC compressor rpms.

 

I have to add a solenoid to keep the rpm up when the AC kicks in myself ...as the car is set up to idle at only 400 rpm ... and a noticeable drop at idle when the AC kicks in ...
Found a cheap (new) electric solenoid on Ebay for only $20 that I can modify ... original equipment for ...
"Idle Stop Solenoid Rochester Quadrajet Carburetor 75-83 Buick Chev GMC Pont Olds"
I'm smiling now ... as see it listed for $90 from some suppliers online ...
I'll run a single wire from the AC compressor to the solenoid ... so that it will kick in whenever the compressor is running

 

Good info

 

For anyone considering a similar solenoid installation to up the idle when the A/C kicks in ... this is the bracket and approach I used for a Carter WCFB carb ... with a lot of linkage in the way ... its tighter than it looks ...