Wedge TR7 Air conditioning help / books/ manuals?

[justin_mercier]

So I fixed every problem with my wedge this weekend but one. I dont yet have the air conditioning working, but all the TR7 books I have (like Haynes manual) dont have anything at all about the air conditioning systems.

I'm 99.9% sure that all the components are there in my wedge, and my replacement belt for the compressor should be here sometime this next week. I dont know if I can flush the system and recharge it with modern AC Coolant or if I've got to find the now illegal to buy or sell R12 Freon somewhere.

I dont want to try to start up the air conditioning until I've at least been able to check over everything. The hoses all look in like-new condition, the compressor clutch pulley turns freely, but without a manual, I have no idea what I should be really checking before trying it out. Does anyone here have experience with TR7 factory AC units, or know of any good resources for me to read up on then?

 

[TFB]

First thing I would suggest is get a set of gauges and see if there is any pressure in the system.If not you need to get a vacuum pump on it.
Once you get the system evacuated and in a vaccuum you would turn off pump and observe that system holds vacuum,then you can decide about replacing refigerant.
However you really shouldnt hurt anything if you put on belt and start engine and turn on ac.If system pressure is low the electric clutch will not pull in(low pressure cut-out).You may get lucky and it will blow cool.You should get about 17-22 deg. temp drop across coil.This is general info,but most auto air is similar.
Tom

 

[WedgeWorks]

You need the red factory TR7 shop manual or a brown bently manual that had all the info on the AC system. I find that it gets real expensive real quickly. Once you touch any part of the sealed system its all down hill. Good thing is that a majority is available still.

 

[Got_All_4]

I am not an air conditioning expert but part of my job is selling AC components like o-rings, orifices tubes, gaskets and fittings. I always ask a lot of questions. I do know that if you can even find R12 refringent you'll pay through the nose for it and must be administered by a licences technician. The new R134A should work in your system however you will have to add the new compatible compressor oil.

R134A is much smaller molecules and the system must be 100% sealed or you will loose the refrigerant. Do what TRB subjected and also get that TR7 factory manual. Your best to leave it to the professionals.

 

[justin_mercier]

I just found a 1978 copy of the brown Bentley manual on ebay for 15 bucks so bought it =) I figure since the AC is the /only/ thing not working in my wedge, that I ought to work on getting it running, particularly since it's a coupe, so AC is extra nice.

 

[TR3driver]

The new R134A should work in your system however you will have to add the new compatible compressor oil.

It's also best to replace all the soft refrigerant lines (the originals may not hold R134A) and the filter/dryer. And the result still won't work as well as the original R12.

There are some other less common alternatives:
https://www.vettenet.org/acfaq.txt

 

[justin_mercier]

In reading, most R12 systems only had a low pressure cut off switch, but R134a systems have low and high pressure switches. If i am going to convert to the new coolant, should I also retro-fit in another cut-off pressure switch? I'm not sure yet, looking at the info that i DO have, whether the TR7 switch is a high or low pressure switch, or even both.

 

[TFB]

Justin,Personally,I wouldnt bother.If you do convert and put in correct charge and high and low pressures are ok,not much chance of of needing hp cutout.
I Dont know how far you have gone with troubleshooting,but you can even try to turn it on without the belt.
If your clutch pulls in you may be ok when you get new belt.
Tom

 

[justin_mercier]

The compressor solenoid engages the clutch when I pull the AC button, and the clutch pulley turns the compressor over freely. Is the electric condenser fan supposed to automatically engage when the AC switch is pulled, currently it does not?

The previous owner equipped a separate fan switch to control the electric pusher fans in the front so that he could turn them on when stuck in stop and go traffic on the cape, where the engine fan doesn't move a lot of air on a wedge, particularly at idle.

I guess when I get the new belt I can hook it up, fire up the engine, and see if I get cold(er) air >_<

For all I know the system was working when the previous owner disconnected the belt, and could still be.

 

[TR3driver]

I don't know that your TR7 would be the same; but on the Stag AC, the condenser blowers run whenever the controls call for cooling. The Stag has a high pressure cutout (the control thermostat functions as a low pressure cutout).

Those old York compressors almost always leaked a bit (just like Triumphs), so I'd say the chances are just about zero that you will have a refrigerant charge left. Common practice "back when" was to have to top them up every year or two. Plus the expected lifetime of the hoses was only about 10 years.

 

[mailbox]

Old hoses won't hold freon either R12 or R134a. Replace ALL hoses, ALL o-rings, drier and expansion valve. Flush out condensor and evaporator cores, drain any oil out of compressor and replace with 134a oil. Smart money says the compressor will need to be replaced too. Vaccuum system out for at least 30 minutes, close gauge valves and let set, preferebly overnight. If it still has the same vaccuum as yesterday refill system. I don't remember the amount to go up to with 134a verses 12. I THINK the drier has a small window on top. If it does the quick and dirty way to fill the system is to fill until there are no more bubbles in the freon stream as seen thru the window. Add more condensor cooling fans if possible.. Most new systems use much larger condensors than the old R12 systems used. It won't be as efficent at radiating heat as the bigger 134a condensors so more air across it will help. It's been several years since I've worked on one and things have changed, but this SHOULD help a little bit.

 

[SpannerMan]

FWIW, I recharged the R12 system in my 92 Miata a couple of years ago with 'Envirosafe' refrigerant ( https://www.es-refrigerants.com/products/w/id/14/t/refrigerant ). No final interest or connection... At that time it was marketed heavily as compatible drop-in replacement for the R-12, and was called 'ES-12a'. From what I saw when I was looking around a bit yesterday, they changed the name to 'R-134a Replacement' to keep the EPA happy. It came with an adapter for the threaded R-12 valve to the R-134a but that didn't work out for me - I made my own tapper/gauge from a R-134a tapper, gauge, and R-12 filler hose.
From my memory, it is a hydrocarbon which isn't terribly harmful to the environment if some leaks out; however, it is flammable. Some consider that to be unacceptable, e.g. in an accident. I personally am comfortable with it. My research at the time led me to believe that simple recharging of an R-12 system with R-134a was a big no-no, maybe OK if you purge the system as recommended. The ES stuff has worked out well for my needs. I have a small leak and I drop a $4.50 can in each year; may get around to fixing it some day. The air blows cold for sure.

 

[71MKIV]

actually the price for r12 isn't all that bad, and dropping, you just need the license to buy the stuff. Ebay has cans for sale betweeen 20 and 40, which admittedly is stupid compared to the .50 that it used to be.

I have a batch of the enviro safe on the bench now to try. we'll see.

The problem with the 134 is that the sizes of the components are wrong in an r12 system. 134 doesn't work as well, so you need higher pressures, and it doesn't give up it's heat as well so you need bigger condensors and fans. 134 in a 12 sytem works ok when lots of air is moving through the condensor, but you warm up considerably sitting still, your pressures go up to the point that you are going to find every weak point in the system.

You aren't going to go wrong replacing all the rubber parts, but a plan on how to proceed might be in order first.

I dunno if the tr 7 system is a fixed orifice type system, but if it is there are special "variable fixed orifices" out there to replace them

 

[DanB]

Justin,

Clay Thompson has the manual posted on his download site, https://public.me.com/jclaythompson

Now, to the AC...
When I got my 7, it didn't work. After much discussion and asking questions, I finally got an answer I liked. According to one AC guy, the R12 oil and the R134a oil won't mix, but the R134a oil will force the R12 oil into the the hoses and help seal them. So, I charged the system with R134a after changing the drier and putting the ether oil in the compressor. It worked the rest of that summer. In the fall, the York compressor died. I didn't know it died, because it would still turn but I got no cold. I took it to a shop, who said it was fine but I needed an expansion valve. I got the valve, ripped out the dash, spent a day putting in a new valve and flushing out the system. At the same time my brother was flushing his John's Cars conversion system with a GM rotary compressor on it. Well, we charged both systems, his worked, mine didn't. Looking at the gauges, we deduced that the York was not compressing. That is where I am now, ready to change out the compressor. I have a Sanden, but need connections and am waiting on information from APAir.
Probably my York compressor was not getting enough lubrication, which caused it to fail. Anyway, it didn't work before it was charged, so I got a summer out of it. I probably didn't need to replace the expansion valve either.
So, you can do like I did and go the cheap route up front: Change the drier, change the oil in the compressor and charge with 134a, and see if it works for a while, or you can spend a bunch of money, replace hoses, compressor, etc. Be aware that the enviro stuff that is flammable is most likely propane.

Good luck,

Dan B
S. Charleston, WV
66 TR4AIRS EFI
80 TR7 DHC broken AC

 

[Don_R]

reminds me of my friend that charged the A/C in his Olds with R22..

Worked great for the summer, system had a leak, we could chill our adult beverages in the dash vents. R22 was also listed as flammable...

 

[TR3driver]

From my memory, it is a hydrocarbon which isn't terribly harmful to the environment if some leaks out; however, it is flammable. Some consider that to be unacceptable, e.g. in an accident.

There was lots and lots of argument over that point some years ago. The dirty little secret is that even R12 will burn quite readily, when mixed with compressor oil and sprayed through a leak/rupture. Here's a little demonstration put on by a friend of mine from Purdue.

 

[DanB]

Well now, we wouldn't want anything flammable under the hood, now would we? ; )