tb wrote:
I just got this car and don’t know much about the climate control
history, other than being told the HI fan speed didn’t work. Turns
out that in addition to that, the unit may not turn on at all, or may
turn on and blow hot air, rather the a/c as requested. Sometimes the
a/c does work–in the ‘auto’ mode.
‘Sometimes’ is a key word, Thon…
The ‘come-and-go’, sometimes arbitrarily change between heating and
cooling, is typical for a faulty AC amplifier. Based on sensors; the
amplifier turns a servo to the appropriate position, and cams on the
servo operates the various functions via pushrods, microswitches and
vacuum valves. The AC amp/servo operations are separate from manual fan
speeds. To test amp;
*Turn ign ‘on’ and set function switch to ‘auto’. Turn the temp control
alternately between ‘65’ and ‘85’. Each and every(!) time the temp
control is reset between these extremes you should hear the servo
‘buzzing’ indicating a functioning amp/servo. Failure or intermittent
reaction is usually an amp fault - which must be then changed before
further work on the system…
The manual fan speeds are operated by microswitches on the function
switch (‘lo’/‘hi’). The microswitches then apply energizing power to the
relevant relay (a common ‘energizing ground’, black/blue fro three of
the relays is grounded by the function switch in all positions but
‘off’), and the respective relays then operates the fans from the 50A
fan fuse. In ‘auto’, microswitches on the servo operates the relays for
two ‘other’ speeds, we can call them ‘auto hi/low’, bypassing the manual
controls. The 4 relays required are placed together in a relay bank, and
only one relay is active at any one time…
The different speeds are then obtained by using a resistor unit; power
from a relay is passed through the resistor unit - connected
respectively to give the resistance required for the fan speed/relay
engaged…
The multiple connections at the relay bank is very critical - and as Al
implies; you need a wiring diagram to sort this fully. Usually one
simply ‘cheat’ by using the original connections, but in your case this
is ‘unsafe’. Again as Al says; a PO might have done a ‘funny’ - and
there is no way of telling ‘what’ and ‘why’…
The best way out of the wilderness is to access the resistor unit - you
will find the green/slate to the manual 'hi’speed relay co-connected
to the green/slate going to the fan motors (NB, below). Point here is
that the green/slate to the motors carry all power to them after
passing through the resistor unit - the ‘hi’ relay simply bypasses the
resistors, to give full motor power…
The other colours on the resistor unit; yellow, blue and red -
goes to the respective relays. But sorting the relay bank connections
from scratch is a daunting prospect, and ‘impossible’ without the wiring
diagram - and even then; wiring diagrams do not necessarily show the
actual physical connections.
Principally; the ‘manual hi’ speed relay should have at least two
external wire connections; green/slate , power out to the motors, and
black/white, relay power from function switch. Nominally;
black/blue, relay ground is internal, as is brown/white, fan power
from the 50A fuse.
NB, the green/slate may be co-connected at the relay rather than at
the resistor unit, check(!) - this may explain two ‘greenish’ wires at
the ‘hi’ relay. As Al says; there are no ‘LGS’ wire shown in the
diagrams…
What ‘may’ have happened is that a PO disconnected the ‘manual hi’ speed
relay because it failed ‘closed’ giving permanent high speed (which
doesn’t explain their ‘burnt’ appearance). With just a failed ‘hi’
relay; all other speeds should operate normally if the green/slates
are disconnected, but(!) kept connected together.
There are no ‘main’ relay - the relay bank consists of 4 independant
relays, which may fail singly.
And I don’t expect you to sort this from these descriptions alone…
Frank
xj6 85 Sov Europe (UK/NZ)> In looking at the main blower relay, I found the two GS wires, or in
my case 1 GS and 1 LGS wire, were not attached to the relay. The
female connector on the wires looked like it had been roasted, and
though not fused together, the two green wires were stuck together
like they’d been thinking about becoming one. I cleaned everything
up, put on a new female connector and attached it to the relay
terminal. This caused the fans to come on, on HI, I think–without
the ignition on, and with the Mode switch in the off position! I
removed the BW wires from the relay and tried again. Same result.
Does this maybe mean the HI speed relay contacts are fused together
in the on position?
The servos haven’t worked for days–though they did today–and I’m
suspicious I need a new amp based on the erratic nature of the beast,
and am in the process of getting one. Should I get a main blower
relay at this point also, or do I need more testing
===================================================
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// please trim quoted text to context only
--you’re the a/c
I didn’t see any labeled as
I didn’t see any labeled as