C4 1990 AC problems and solutions.

[Vettech]

Well as previously discussed my 90 A/C is running very well with the new "Hi-Chill -30".
Only issue is Air Flow Volumn - but this can wait.

In the meantime I've found another 90 to tinker with. The usual checks show flashing led on AC Controller panel. No cooling.

Put the guages on the system, virtually no gas. The original system had R134a and PAG Oil, so is compatible for HC-30 to drop straight in.
However, we cleared and sucked down the system to 30" of mercury. Appears to be holding vacumn.

Dumped some HC-30 in, system came to life and the A/C clutch started quick on & off cycling - then system cuts out. Brain goes into overload.

[Vettech]

After sleeping on it and researching Dr Google I realise I'd forgotten a thing or two. Alsymers is catching up.

We will need to access the A/C controllers code - turn on ign, put AC in Auto mode, press both up & down fan switches for 5 sec.
Display will indicate "00" then use "fan auto" switch to scroll thru possible faults - hopefully only one code ' "09" ie no or low refrige gas charge.

If this is the only code, then we need to reset it, simple, disc battery/earth for 10 mins.

Gauges etc connected, as long as enough gas pressure is indicated, start car, switch on AC. (RECIRC, MAX FAN, LOWEST TEMP)

Should now cycle up and start cooling.

BUT ☆ there is always a but - prior to doing any of this - I think it may be prudent to open the system and check the "Orific Tube" and or just replace it.
$10 item with a very small hole (0.052 - 0.0☆☆) which does not take much to block it and its screens.

We have all the gear, gauges, hoses, manifold, Vaccum pump on site, ummm.....

[Vettech]

Well followed my own advice.

His 90 has better airflow than mine, and the air is now very cold - success.....

Good feeling when a plan comes together with a good outcome.

Cant wait now to get back into fixing my 87 which will also include Hi-Chill 30 A/C.

Regards.

[Scott]

Good to hear the feedback regarding the hi-chill stuff.  I have a few cars that will get some of the same when I get to that point.

[Vettech]

Here's a tip for you.

My 90 is a chain and bar conversion - as far as the engine bay goes, there are no big changes to see, but the Dash and everything behind and under it is another kettle of fish. But it does mean that all A/C bits on the engine side are as per OEM - thus parts are widely available.

My 87 on the other hand is a Mirror Conversion - ie everything has been butchered everywhere. Having owned/had a number of early GM Commodors I recognise the similarities to Corvette A/C, so by using a VB SLE Accumulater which is identicle to the 78 & 87's accumulater, BUT has reverse pipe connections (makes for very much easier hose runs) because the VB is built as RH Drive, also the heater/evap matric & fan housing is also designed for RH Drive. Converters normally rip out the AC housing and turnover 180° and fit to the lelt hand side, but alas it is now upside down - with resulting cut and paste to make it work.

I believe that a Comodore A/C housing & accumulator fitted would allow all the original functions to operate at their intented specifications.
This I will try firstly with the 87 which has to be back on the road very soon.

My 90 gets cold, but vent air flow is minimal - even though the fan is on high and sounds like a 747 taking off from under the dash, obviously we have restricted ducts and or vents. Not sure I will ever fix this issue before it goes to a new owner. But I expect the 78 once completed will function to spec, and more than likely utilise several Comodore AC parts - seems strange to even say converted C3 with working AC.

Anyway - just some food for thought.
Regards.

[MY081]

Thank you  uncle Doug . I do absolutely nothing on my Vette ( Mechanic Do'es ) but I fine your Posts very interesting . Go figure ****>>>> ? Ray

[Vettech]

A recent 90 I converted to run on Hi-chill -30, suddenly stopped running or more correctly stopped making Cold.

I must admit my heart dropped a beat, its great to fix the unfixable, but when it plays up again, you start the self doubt and second guessing.

Upon visiting, the guages said plenty of gas, pheew, thats good, the last thing I want to find is a hole in the evap, or for that matter any leak.

System would not start the Compressor, some basic checks pointed to the Hi-press Cycling switch located on the liquid line into the evap.

This type are good as they can be removed without breaking into the system (Schreader Valve connected), had a fiddle and the contacts were every resistance value except open or closed circuit. As luck would have it - I had a spare. Fitted it even though its set up for R12, put a few gramms more gas in and away it went - cycling the compressor like a bought one - the owner tells me the inside vent temp is now even better than before. I think it may actually be too cold - we will see.

Before it was cold - now it's "bloody cold".
.

Very soon I'll be working on my 87, parts are due in from "CC" hopefully this week.

[MY081]

Tell Tony to  put a Cardy on .Ray