AC: f*ckung freezy or horrible hot?

[tomcat22]

Hi again,

in the german forum there are two mechanics who were working for Rover until the collapse. They say the V8 has a buggy electronic, diagnostic is not as good as on other 75s / ZTs.

Many issue they complain is the air condition, it would only work between the two extremes mentioned above. I can not judge this, because the 3 V8s I saw I drove them only short-time.

What do you say?

Tom

[colintf]

some are good others are not so good.

We have a fix for it though I believe Tom

[2V8s]

yeah its a common thing more so for the temp to always blow hotter than it should, which is caused by the heater valve and there is a fix developed by a member on here and available through the club shop. Not caused by electronics.

Although some people do occasionally experience a wierd occurance of hot and cold switching around and / or hot and cold one side versus the other. I had this once but after switching ignition off and back on it sorted it's self out.

So over all, not a big problem really but something to check that the a/c blows cold when set to low. This is hard to guage in winter when the outside temp is low. Best to use the car, get all warmed up, and then let it sit parked for a few mins.

Then start the car, deactivating the a/c, leave temp sety low and you will find the air coming in feels warm due to the heat coming up into the plenum chamber from the exhaust on the LH side. Activate the a/c and if it swiftly gets cold, this should indicate the a/c is working OK.

[ksilver]

Hi again,

in the german forum there are two mechanics who were working for Rover until the collapse. They say the V8 has a buggy electronic, diagnostic is not as good as on other 75s / ZTs.

Many issue they complain is the air condition, it would only work between the two extremes mentioned above. I can not judge this, because the 3 V8s I saw I drove them only short-time.

What do you say?

Tom

That's 2 separate issues, the heater valves stick, either full on of full off, which one you get is usually dictated by the time of year when it is guaranteed you will want the opposite of what you get!! As stated the club have a fix (Thanks Steve!)

Electronics/diagnostics, the normal T4 diagnostics system was apparently never coded properly for the car and may not work as it should. I am sure I have read somewhere the best thing to do is to deal with one thing at a time (in the diagnostics) and not overload it, but I have no experience on that.

[Herman]

As you're still not green, here is the ATC check method, no T4 needed

Copied from the index section

How to run the ATC (Climate Control) Diagnostics checks
I have copied this from the The 75 and ZT Owners Club Forums, thanks must go to Mike for the information:

Running this routine performs a full check on the ATC system including the sunlight sensor.

to start the check:

1. Press and hold the AUTO switch and the air distribution switch and then turn the ignition switch from 0 to II.

2. The audible warning and all indicators on the control panel display cycle on and off while the ECU runs the diagnostic check.

3. On completion of the check the display shows FC in the LH temperature window and a two digit fault code in the RH temperature window.

4. If there are no faults, the system will revert to normal operation.

5. If a fault is detected, an audible warning sounds three times and the fault codes cycle on and off in numerical order. The audible warning will sound as each fault code is shown.

6. Cancel the check by pressing the OFF switch or turning the ignition switch to 0.

7. In low light conditions to avoid false sunlight sensor fault indication the sunlight sensor (centre front of dashboard) needs to be illuminated with a strong light source.


Fault code and description

00 - No fault found -

11 - In-car temperature sensor open or short circuit 25 °C (77 °F)

12 - K bus fault with ambient temperature input 10 °C (52 °F)

13 - Evaporator sensor open or short circuit 5 °C (41 °F)

14 - Heater coolant temperature sensor open or short circuit 70 °C (158 °F)

21 - Sunlight sensor, left output open or short circuit no solar heating correction

22 - Sunlight sensor, right output open or short circuit no solar heating correction

31 - LH temperature servo motor open, or short circuit, motor or flap mechanism seized, servo motor locked in position.

32 - RH temperature servo motor open or short circuit, motor or flap mechanism seized, servo motor locked in position.

33 - Distribution servo motor open or short circuit, motor or flap mechanism seized, servo motor locked in position.
__________________

[tomcat22]

thank you all for the information.
can't wait to become green and see the workaround from the club shop

@VMax1000: the heater valve stick is not listed in the fault table, but I already heard that, turning the AC to max heat for cooling down

[black olive]

yes the valve fails but we have a long term fix

[tomcat22]

will now go for the long term fix, as now my mechanic says its horrible hot always