Hi all.
Just replaced the LH blend motor and the book symbol has now disappeared 👍 But I still have no aircon. 😡 I assume the next step will be to see if we have gas in the system. Also will I need to have any faults on the HEVAC cleared. I will get myself a Nanocom at some point so I will be able to sort this sort of thing myself.
Cheers.
Rob.

If the book symbol has gone, you've no current faults (although there will probably be loads of historic ones). A lack of refrigerant won't usually bring on the book. Does the compressor kick in? Simple check to see if there is any gas in it is to poke the Shrader valve in the fill port. If nothing comes out, it's empty. If it is full, you'll lose a little but not enough to cause a problem.

Thanks for your reply. No the compresor doesn't kick in never has since I have had the car. I assume the compresor won't work if there is not enough gas in the system.
Rob.

No it won't as the pressure switch won't let it. However, it isn't unknown for the connectors to the pressure switches to go bad so it still won't work even if there is gas in it.

I will have a poke with the valve tomorrow and see of there is anything in there. Can I ask is the pressure switch the tri switch and can these be replaced with gas in the system. Thanks again for all your help it's very much appreciated.
Cheers
Rob.

There's two, a single pressure switch and the trinary switch. Trinary has a Schrader valve behind it so can be changed with gas in the system, the pressure switch doesn't.

The Trinary (dual pressure) switch is the one that controls the clutch and condenser fan speed. The single pressure one powers the condenser fans.

The dual pressure switch protects the refrigerant
system from extremes of pressure and controls the
operating speed of the condenser fans. The dual
pressure switch is installed in the top of the receiver/
drier and senses receiver/ drier outlet pressure.
If the minimum or maximum refrigerant pressure limit
is exceeded, switch contacts open to disconnect the
power supply line between the ATC ECU and the
compressor clutch. The minimum pressure limit
protects the compressor, by preventing operation of
the system unless there is a minimum refrigerant
pressure (and thus refrigerant and lubricating oil) in
the system. The maximum pressure limit keeps the
refrigerant system within a safe operating pressure.
A separate set of switch contacts control the operating
speed of the condenser fans.

When mine had no gas the HEVAC had a fault code saying the compressor was open circuit (because the pressure switch is in series with the clutch)

However i think later cars maybe run the compressor clutch thru a relay, so the HEVAC unit doesnt "see" that its open?

put 12v directly to the compressor and see if the clutch engages. at least you can then rule that out.

What Aragorn said - the early cars that drove the compressor clutch directly from the HEVAC will throw a book if the gas is low. Later cars that drive it through a relay had this 'check' programmed out in the HEVAC (because the load of a relay coil being far less than that of the clutch).

That's why you can't put a relay on an early HEVAC without a big resistor to dump current into (part of the factory loom fix/upgrade thing), and similarly can't put an early HEVAC into a late car. You could put a late HEVAC into an early/no relay car though and it will work, and you won't get a book if the gas is low enough to not run.

Hi all.
Thanks again for the replies. Another quick question. What is the best way to remove the fan switch to replace the bulb. I have read a bit on RR.net and it says to just pull the switch straight off. I have tried this but mine doesn't seem to want to move. I suppose I could pull the HEVAC apart just a bit worried about the LCD.
Cheers
Rob.

squeeze round the knob with your thumb and finger until you find the point where it flexes. then pull it off t same time as squeezing.

Pull the unit apart and use one of Martys ribbon cable replacements when you put it back together. If the screen pixels haven't started dissappearing yet they soon will!
You can then clean all the rotary contacts replace all the bulbs and it'll be good for the future.

Sorted the bulb ta. It's all back in the car now and seems fine. Thanks for the tip about the ribbon cable if the LCD does play up I know where to get it sorted now. Next job check the AC gas etc. Thanks again for the help guys.
Rob.

Well checked the gas today by pressing the valve guess what yep it's empty. Next job to take it somewhere for a fill and see what happens I suppose.
Rob.

Well had the system refilled today and it now works fine I have climate control. £39.00 at the local Wilco / Fast Fit.
Cheers
Rob.