GTV AIR FIX

[MD]

Where do I start !!

I have lost count of how many posts I have read from frustrated 116 series car owners who complain that the air conditioner in their vehicles is next to useless. Many owners decide to embark on simply making sure that everything is well serviced to original specifications and hope to hell it will do the job. It won't. It never did when it was new.

Others still make improvements to one aspect or another making marginal improvements but never actually transforming the system into a good set up adequate for the Australian climate. The most recent article I read was from Luke C who has had a good crack at dealing with the fundamentals of what is wrong and achieved at least a major improvement in the creation of chill albeit at the price of originality which I am afraid is part of the course. If you are expecting improvement but insist on the car staying original, the outcome of your efforts will be less than satisfying to say the least.

Accepting the need for considerable adaptation, modification and the like to come up with a good system is likely to have the concourse judges give your car a wide berth. The choice is simple. Functional air or originality. You cannot have both.

Understanding the problem

Here is a list of what makes the 116 series air conditioning a substantial challenge to upgrade using the existing hardware:-
1.   The GTV's have a very large glass area collecting more heat than the system capacity was designed for. There is also a lot of radiant heat coming from the exhaust system up through the floor. This requires lining of the transmission tunnel with insulting material such as laminated aluminium sheeting. If you have an engine conversion and utilising a catalytic converter, this would produce a lot of heat which it is supposed to do to incinerate pollutants but you need to deflect this. The firewall is also inadequately insulated transferring engine bay heat into the cabin.
2.   All these heat sources create a big heat load to dispose of outside of the cabin. The stock serpentine evaporation and the condenser units are lower in heat exchange efficiency than the modern parallel flow units fitted to contemporary cars.
3.   A serious design flaw in the evaporator/heater box assembly causes short circuits in air flow around the evaporator unit instead of through it making the heat absorption function very poor. This is due to close packing of the heater core against the evaporator core and the placement of the fans in a drawing mode instead of a pushing mode. The solution to this is to remove the heater core altogether and install a separate heater box with fan –more drama. Less drama is to install an electric element in place of the water heated core in the original evap. Box (if you can still get one). If you live in the tropics, just leave it out.

4.   The thermostat calibration is so wide that the system will drift up to 9 or more degrees before it kicks in the compressor to create further chill. This has the effect of being hot and cold in the cabin no matter what the temperature setting is. Anotherwords, it cannot create an even and consistent temperature climate due to the wide calibration. A 3*C swing makes for a good stable cabin temperature and to do this will require customising the settings on the thermostat if an off the shelf replacement cannot be sourced. Not a DIY job.
5.   There is no de-icing mechanism to keep the evaporator from icing up and reducing air flow even further. The effect of this is that the cabin temperature starts off being acceptably cool at a given setting only to find that the cabin temperature is progressively rising as you drive along and turning the setting further down produces no cooler effect. After you park the car and take a lunch break, you can see a pool of water under your car which is the melted ice that was clogging up the evaporator and reducing the chill function. You drive off and the air conditioner is making chill again for a while....Modern cars de-ice on the move. Depending on your location and the level of humidity, the icing up issues will be minor or substantial.
6.   Air speed and volume. Both these criteria contribute to good cabin circulation and heat scrubbing. Remember that you are taking heat out of the cabin and not putting chill into it (although the effect seems that way) The fan size and power is not sufficient to produce the volume and air speed required. This is a major flaw. The fans in the 75/90 are identical but produce a better outcome due to their push mode. The lack of air volume compromises the ability to create air delivery in ducted systems to face level air registers and any expectation for a dual zone delivery is just out of the question.
7.   The fan location produces excessive noise at any speed.
8.   The cable operated heater control valve tries to do the job to shut off the hot water supply to the heater elements in the evaporator box. It is rarely 100% effective and in a cold climate, this would be a welcome flaw. However in Oz, all that it is doing is creating even more heat load. This unwanted heat would actually help in a de-icing function if the core was placed in front of the evap. core so that the fans would continually pull warm air over the evap. core. Regrettably, it is located "downstream" of the evap. core and therefore completely useless in this regard.
9.   The air registers that are available are poorly positioned so that very little is delivered to the upper body and even less to the face as the air speed and volume are not capable of effectively doing so.
10.   Finally, the original reciprocating piston compressor (if installed) together with its cumbersome mounting is best utilised for a boat anchor.


Our Mission

Our mission is threefold:-
•   Reduce heat load.
•   Increase efficiency
•   Improve distribution
With respect to heat load reduction, do not be tempted to apply window tinting film as a major cure. Glass already filters out around 96% of ultra violet light. What we are interested in is infrared radiation which is responsible for heating up the cabin. Window tinting does not filter infrared unless it is the mirror reflecting type. It is illegal to install in your car.

Crunch Time

Having outlined the problems of the system, it is too arduous a task to detail every modification that needs to be made so as to completely redesign the system. After all, I need all you thinkers and tinkerers out there to get a bit creative yourselves. Where's the challenge in a cheque book I hear you say?
What I will do is to take you through a photo collage of how I created a much improved system to my GVT6. The result is not perfect but it does the job very well. Tabulations on the photos explain what is required. HOW you go about it is a plan of attack for you to plan out.
This article was considered as an afterthought otherwise I would have been able to provide a detailed progression of every work stage that I am sure would have been useful. The best I can do is to show you the final outcome. Knowing the objective will help you devise a process.


What's it worth?

Bear in mind that this work is not for the faint hearted and requires some serious application if you are going to do it well so that it not only works well but looks acceptable too. The cost of the project needs to be borne in mind with the overall value of your vehicle which could be easily exceeded if it is a fund raising special. On the other hand, a serious commitment to the brand and model warrants a solid attempt that will add value, comfort and enhancement to your car. A ground up budget to have a professional workshop do this work for you would be in the order of
$3 000 - 5 000. Carrying out the work and buying the new components at trade price would see your costs in the range $1 000 -1500. These costs do not include the cost of any coachwork.
If you have a good mechanical skill level as a hobbyist, it should be possible for you to undertake the overall installation and partner up with a professional workshop to complete the wiring and gas installation. This would provide considerable savings in labour costs.
Ideally, this level of modification and upgrades would be best undertaken during a ground up restoration facilitating the installation of firewall and turret insulation and customisation of various parts. For your trouble, don't expect any mercies from the concourse judge.


Proof in the pudding

Recently I had a fellow Club member who drove my car for an hour or so had a solitary complaint. The air-conditioning was too cold on a Queensland summer day.  A complaint that I can tolerate with some pride.

MD

[MD]

Continue photos.

[MD]

Interior issues

[MD]

Continue with interior issues

[gtv6sv]

Absolutely fantastic read MD! Fantastic job you've done and a fantastic car you have there!  I'll definitely be keeping all the insulating and venting ideas in mind for when i restore my GTV6!

[MD]

Thank you.
After contributing various small segments to scattered projects on this and other forums concerning air conditioning to the 116 series, I realised that the topic needed a definitive and comprehensive summary of all the issues that outline both the problems and the solutions in one go.

I have given it  my best shot and sunk the funds in to follow my convictions through. I am glad you have obtained some inspiration from my post.

If I get some free time, I might detail a cousin project to an Alfetta Sportiva that I did some time back with a completely different approach which may produce further inspiration in a different direction. Equally complex but cheaper.

Then there's the 75 v6 that I worked over...

[LukeC]

I'd seen a couple of your other posts on A/C in one of these. Good stuff...

I am assuming you installed an after market fan evaporator box where the parcel shelf is.

I considered installing a perspex divider behind the rear seat to block off the rear hatch parcel shelf area (mounted on the CRAs). But I decided to see how it went first. Happy so far...

I think the size of the aperture from the scuttle into the cabin is a big issue when the ventilation control is not on recirculate in the standard car. I also noted the scuttle opens into the structural legs and inner guard space. I was reluctant to seal this for rust reasons and figured once on the move there is always positive pressure in the scuttle.

I am going to rebuild my front exhaust shortly (custom headers etc), and will be using a 75 Cat heat shield underneath.

2 things off topic:

Looks like an '83 2.0 originally? I have often wondered if a 164 plenum would require the GTV6 bonnet. Looks like it doesn't (Q-car).

Seats remind me of a pair that were in an E38 R/T that I considered buying in my pre-Alfa days. They were pricks of things to get in to....

[ALF750]

A big job MD...glad it works.   The ball valves on the heater hoses is a great easy idea!   Did you use flourocarbon gas again or hydrocarbon/Hychill?   I've put Hychill Minus 30 in my 75TS with the standard R12 compressor and found it works pretty good, and doesn't leak out like the R134a does.   

[MD]

Hi Luke C,

I mentioned your contribution because you are the first person I found that was digging in the right place to try and work through the core issues instead of tinkering around the edges. That sort of commitment needs recognition.

The system in this car is 12 years old and has covered around 20 000 Km on the original 134a gas using all new reticulation  components other than the evaporator. It hasn't yet required a service but I am going to give it a 2016 present.

The system uses the original evaporator/heater box assembly. The leather covered insulated ducting under the glove box delivers chilled air to the passenger side eyeball register. It had to go there so that the glove box function would be retained.

Since 2003 when I built the system, new insulation materials have come on the market which I could have made use of to line the transmission tunnel and apply to the firewall on the engine side but that's the breaks.

A transparent divider for the rear parcel shelf would help a little.

You are correct. The car is a re-engineered all over 1983 2.0 using the  shell I prefer and it has my preferred split dash which I have written about elsewhere. The 164 conversion was straightforward and I managed to keep the original bonnet for a stealth mobile 

The seats are the original GTV seats completely stripped down, with modified frames, cushioning and contours tailor made for a "his" and "hers" fit and finished in black kangaroo hand picked hide. Like racing seats, you just cannot slide across them but then, you don't slide out of them either when things are perculating..

[MD]

ALF750
The ball valves are a simple fix but you do have to remember to turn them back into flow mode during the winter or in cold regions of Oz. I use 134a gas with all new parts designed to be used with this gas.  I do not want to go into a discussion about other refrigerants.

[Davo416]

Hi MD - great write up,thanks for sharing. Every time I visit Brisbane in summer it reminds me how necessary decent air con is up there!

I'm in the middle of stripping out a GTV6 shell and intend to use a sprayable microsphere system on the inside of the cabin for a thermal barrier.

"....new insulation materials have come on the market which I could have made use of to line the transmission tunnel and apply to the firewall on the engine side but that's the breaks...."

....and this question is on my mind - what is the best option for the engine bay side of the firewall?

[MD]

Hi Davo,

There are many forms of pliable insulated sheeting that would do the job. However the majority of them contain an insulation material sandwiched in between some aluminium cladding comprised of one form or another of a petro chemical. This material in time will break down to its original substance and therefor has a limited life span . It is also not very robust and may puncture during service events.

What I would use is a rigid insulation sheet generally used for exhaust cladding and turbo shielding:
http://www.carbuilders.com.au/embossed-aluminium-heat-shield

The way to apply this material in the first instance (with the engine out) is to make up a cardboard template to fit  the firewall. From the template, make the actual insulation cutout and simply stainless rivet fix it to the fire wall.

Keep in mind as  I have said in the main article that there is a coachwork fabrication foul up that funnels hot exhaust air up inside the inner guard chassis brace running from the engine mount back up to the top of the firewall. At the very top of this fixing, there is an entry (cannot be seen) that allows engine hot air continuously to enter the cabin via  the fresh air vents !! Hence this inner guard rail needs to be expansion foam filled to block this hot air as shown in the photo.

If you want to do eliminate another huge source of radiant heat, also line the transmission tunnel while you are at it starting from the firewall back.doing this would be more effective than just cladding mufflers as the pipes themselves are addressed at the same time.

You may care to read this :

http://www.european-aluminium.eu/wp-content/uploads/2011/11/AAM-Applications-Power-train-6-Heat-shields.pdf

[Duk]

Hey MD, what's with the compressor on the passenger's side, is that how it is in a GTV6?

[MD]

You should know by now that everything I put my hand to gets the custom job. Honda compressor on a 164 donk.

[LukeC]

Modern Japanese A/C compressors are tiny! Not saying the Sanden on the 75 is modern, but while I was half way though doing my A/C install, my clutch in my Subaru went. The best way to do a clutch in a Subbie when you also want to do belts is to take the engine out (laying the A/C comp to the side). The compressor was miniscule by comparison, but is enough to keep an Outback cool.

I could not be bothered constructing the new brackets for a custom install: PITA remembering when I installed a 164 PS pump in this position, so I just used the stock mountings.