Before major surgery on HVAC

[tvrgeek]

Lots of questions but this is because I am finally working my way through the car finding all the issues. This morning is HVAC, or lack thereof.

Obvious problem one was the vac line to the water valve was split. So I used my miti-vac to open the valve. I got what seems like a bit of water flow as the inlet did come up to temp, but outlet remained only luke warm. So I assume a valve not opening completely. I can also assume a 47 year old heater core is not going to be very efficient. As I got no vac through the control hose, I assume the valve in the control panel is bad. Fans both run, but airflow is horrible. Low is barely what I would call super low, and high totally inadequate even to defrost the windscreen. WHAT IS NORMAL? I want to know if I am fixing things, or need to do major surgery, like replace the entire system with parts from Vintage, Classic or a breaker. Been there, done that, no fun on my TVR. Yes a 2500 with full HVAC inside the dash!

Is the AC in working condition capable of freezing you out in Phoenix? Or is is enough to make the 80 degree day more pleasant as I found is other British cars?

As a reference, in my B, I put in the uprated heater core and a Hyundai fan. Airflow was enough, but marginal heat relative to what I expect for a cold morning. I drive year round so I want real heat when it is well below freezing. My Sonoma does this quite well. GTI is OK.

[tvrgeek]

Confirmed, the vac line to the control does not hold vac, so another split or bad control.

[trunt]

Never seen mine working but have messed around with it a bit. I did check mine out and prep it for possible A/C fitting at a later date.. More than enough to do for now!

My first question would be what kind of gas is on there? It’s likely that by now the original R12 has been replaced with R134, the York compressor, indeed the whole system was not designed for R134 so it’s normal for it to not be as efficient, (I.e not really cold)

The heater flaps are also controlled by a vacuum actuator, is that working OK? On A/C it should divert all air to the Center vent where it passes the evaporator, so if the flaps are not working or leaking it will cause bad flow in either heat or cool. There is a really good description of the whole thing in the ROM.

if you take the water valve off you can actually see how much it opens and check it for leaks easier.
It is controlled by a temperature compensator, I wondered if that can be bypassed and the vacuum from the control Valve used to directly control the water valve? May be worth a try?



Terry

[trunt]

Confirmed, the vac line to the control does not hold vac, so another split or bad control.

maybe the leak is also affecting the flaps?

[trunt]

Mine is installed but no dash at the moment if you need pictures

[tvrgeek]

Flaps actually work but they feel like they are cable.
I see a vacuum controlled generic valve is only about $35. Or I can put in a servo one for $85. Was going to do that on the MG anyway.
Heater valve looks like a really good place to put a purge valve for the cooling system as it is the system high point. I might even have a remote filler cap thingie in the box somewhere.

Started looking at what few parts are available. Crazy prices.
I am tempted to buy a complete Vintage Air Gen IV, tear it apart and make it fit. Servo everything, new Sanden pump and of course, sized for the new coolants. New cars have moved past 134a. Of course, need all new teflon lines. Condenser fans don't cover much area, I think an upgrade there is in order, If done well, might be able to replace the main engine fan with a pair of pullers in a shroud. It looks like I have a lot more space to work in than I have in other cars.

Sigh, looks like a major project, and I just want to drive!

Darn Terry, wish I could take a peak.

[trunt]

The only flap that is cable is the fresh air/recirculated air. The heat/cool is a vacuum control on the rhs of the unit

Terry

[trunt]

The vacuum actuator is in this picture, it operates 2 internal flaps, you can see the one at the top of the pic that opens the centre vent flap and the other is tucked down in the unit, you can just see it bottom left of the actuator. its binary hot or cold, controlled by a valve in the control box. You can also see the temperature compensator just behind the control box it gets a wanted temp signal from a valve on the slider control and uses a bi-metallic strip to control the vacuum going to the water valve thereby maintaning a set temperature.

IMG_3129.JPG

[trunt]

The control box has a valve, left side on the picture that controls the flap actuator. In the center is the heater control valve that sends the vacuum to the temperature compensator. The red switch is to turn on A/C. The A/C thermostat is on the right with its sensor pipe, It controls how cold the A/C gets by turning the compressor on/off at the set temperature. All 4 are controlled by the hot/cold slider.

cool3a.jpg

[tvrgeek]

Thanks. Neighbor who does the sparky stuff for a restro shop in town suggests VIntage Air products are better than some of the competition. I suspect I can stuff a Gen III in there and stil have a glove box. I lose the fresh air intake but I may put a cable on a flapper just as a passive vent.

Started to check on not just things working, but how well. I guess it is SOP, every connection in the car is bad. Starting at the main body ground! I got OHMS in some of the lines. A lot of connecters are going to get replaced with barrier strips. To get to the connections, I have to pull it all apart anyway. Someone was already behind the instrument cluster and made a cluster of it.

[tvrgeek]

Digging my way in. Got the console off so I can get to the controls. Corrosion everywhere. Lots of spliced wires, lots of tarnished plugs. No wonder I had 10 or so volts around places. Just maybe things like the wipers will be serviceable with everything clean and tight. Looks like I should go ahead and pull the entire dash anyway as even if I keep the OEM HVAC, new lines and everything means I have to get to more of it. Does look like there is room for a Vintage Air unit to replace it all. No switch on the the choke cable which is why the dangling connector. Won't bother with that as a Holly TBI is in the future. I see how the temp control works now. Reasonably clever actually.

[tvrgeek]

Quick look the Vintage mini Gen II should fit.. Compac may fit too. Considering changing all the lines, wiring, compressor etc, may be smart. Stock condenser coil is pretty small. Fans not shrouded...