[xj-s] Understanding/Testing Vacuum Solenoid in Mk III Climate ControlSystem

In reply to a message from gbalthropxjs@aol.com sent Sat 19 Apr 2008:

George

Forgive me if you already know this (or it’s not what you’re
asking) but one of my CD-ROMs says, referring to the Air Con
control unit:

output from the ECM:

Digital input levels: LOW 0.16 to 0.56V
HIGH 3.70 to 4.50V
Analogue input levels: GENERAL 0 to 0,2885V

BLEND FLAP POTENTIOMETERS 0 to 5,OV

Digital output levels RELAYS ON 8,OK
OFF 1 .O to 5,OV

VACUUM SOLENOIDS: PULL-IN 5.6V (typical)
DROP-OUT 3.5V (typical)

Analogue output levels
BLEND FLAP SERVO MOTORS 0.5 to 6,5V
BLOWER MOTORS 0.5 to 2.5V

My guess from this is that anything over 6 volts should actuate the
solenoids.–
The original message included these comments:

However, what I was inquiring about is the voltage applied to the
vacuum solenoids which are located, 2 on either side, of the CCU base.
It could be that applying 9V to those solenoids would also actuate them


al mclean '93 XJS 4.0 - '84 4.2 Daimler - '84 DD6
Telford, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

Hi Al,

Thanks for the information. I see it is in the Facelift CD at 82-5
(1991 ROM). I had not been able to find that info in the earlier 1988
ROM for the pre-facelift cars.

As you say, it would appear that it would be safe to apply 9v to the
vacuum solenoid for test purposes, and that was exactly the information
I was looking for.

Thanks again,
George Balthrop, Clifton, VA USA
85 & 89 XJ-S Coupes; 89 XJ40 VDP-----Original Message-----
From: almcl al.mclean@blueyonder.co.uk

George

Forgive me if you already know this (or it’s not what you’re
asking) but one of my CD-ROMs says, referring to the Air Con
control unit:

output from the ECM:

Digital input levels: LOW 0.16 to 0.56V
HIGH 3.70 to 4.50V
Analogue input levels: GENERAL 0 to 0,2885V

BLEND FLAP POTENTIOMETERS 0 to 5,OV

Digital output levels RELAYS ON 8,OK
OFF 1 .O to 5,OV

VACUUM SOLENOIDS: PULL-IN 5.6V (typical)
DROP-OUT 3.5V (typical)

Analogue output levels
BLEND FLAP SERVO MOTORS 0.5 to 6,5V
BLOWER MOTORS 0.5 to 2.5V

My guess from this is that anything over 6 volts should actuate the
solenoids.

// please trim quoted text to context only

George

Did you ever test your Vacuum Solenoids?
I’m tracing problems withe my xjs delanaire III system and have got them out to test.
Did applying 9Vs work?
If so do you know which is the +ve and -ve terminal?
With the mounting plate sitting on the table and the vertical plastic pipe connection from the solenoid pointing upwards is the +ve electrical spade the top or the bottom one?

Thanks for your help

Regards

Chris