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This is my first post, and hopefully I am in the right section.
My car is a 1985 XJ6 Series 3. I have had it now for close to 4 years and have had a relatively problem free time with my car.
My problem is the climate control system is now not working. Originally, the air con never worked but everything else seemed to work correctly. Very recently I can only get ( occasionally ) low fan speed regardless of position of mode switch and only cold air.
I am aware of many other threads on similar issues, but before I go to far I have checked fuses. Here is where the fun starts.
1. On RH side fuse section ( RHD model ) the 50 amp fuse was blank. To be honest, in nearly 4 years of ownership i have never needed to check this fuse. There was nothing on the floor so I am guessing the fuse has been empty all along. Inserting a fuse did not seem to help.
2. LH side cheek panel removed. Refer photos and in the in line fuse holder it was empty too.
3. RH side in line fuse holder appeared to contain a fuse, but a bit hard to get to. So I stopped and thought maybe I seek some help.
When I move the mode to screen setting the system makes usually hissing sound of flaps opening. But no fan.
Intermittantly the fan will blow on low speed ( regardless os position of mode setting )on full cold mode - i.e all dash vents only. Adjusting temperature setting does nothing.
Other - I have previously substituted heater valve with one that has no vacuum connection. Heater valve manually adjusted to full open.
I also replaced thermostat. But an old trick of drilling a small hole in thermostat has resulted in car running very cold ( I previously had the radiator reconditioned with a thicker core. At its hottest car reaches 70 deg, normally 55 - 60.
Previously, the heater and system ( sans air con! ) has worked very well. I could here the servo whirring as the system would progressively adjust heater ( as an aside it was a very good heater ).
My request is given the above, with both the 50 amp fuse and left side in line fuse missing, and the system having previously worked, I am thinking at some point the system has been modified.
I would appreciate if someone could shed some light where to best start. Normally I would think fuses, but as in my first post two of the fuse holders where empty and up until recently the system worked. Now it doesn’t.
to those who know do the photos reveal the original amplifier?
If it is I suppose I can continue normal diagnosis. But any suggestions would be appreciated thanks
Oh boy. First, if fuse holders are empty that is a pretty good giveaway that some person has been in there modifying things and you have no documentation. When I see that I worry that they may have rewired without a fuse which is a potential problem. First thing I would do is figure out where the power is coming from and make sure it is properly fused.
Your photo of the left cheek panel. The amplifier is way up in there slightly to the right of the vent and then up. Almost impossible to see. Get a flashlight and look for a round multi-pin connector. It is about as big around as a nickel. At the other end of that is the amplifier. I believe the amp is sometimes held by a clip but often just stuffed up in there,
The first step is to understand how it is supposed to be, the second thing is understand how your car is wired and setup, the third thing is to fix it.
1) the large relay on the driver's side which contains 4 relays inside, one for each speed. Could be burned out.
2) the blower motors themselves, they get full of grime and stop accelerating.
3) on the passenger side, buried deep in the corner near the floor and the bulkhead/firewall, there is a small circuit board with a thermister that registers the incoming air temperature. This circuit board gets covered in grime from incoming air and essentially stops registering. Remove it and clean it with old toothbrush.
Replace the fuses one by one and see what happens.
Great advice from Jose - start there. Regarding the amplifier, there are no moving parts, adjustments, or any way to test them (other than replacement) so most people don't even try to find them or remove them. If you want to replace it just fish the round connector out with your fingers, plug the new one in and stuff it back up in there (leaving the old one in place for posterity). You don't have to worry about it rattling up in there since there are so many wires and tubes it will be snug amongst them and be fine. Amplifiers are expensive so start with fuses, relays, proper grounding, etc. When everything else is checked and good, then think about the amplifier. Good luck. Most all of us have had problems with the heating and A/C at one time or the other.
to those who know do the photos reveal the original amplifier?
I've attached a pic of the amplifier so you'll know what it looks like. As mentioned, it's a bit buried.
Judging from the pic of the left side I'd say your amplifier has already been replaced. You can see the vacant connector---round, white, multi-pin. It also looks like the mating socket as been re-connected....and the only thing it would connect to is a different amplifier. Probably the 'shotgun shell' replacement style
When I move the mode to screen setting the system makes usually hissing sound of flaps opening. But no fan.
This might be a clue.
In defrost mode the system defaults to max heat and max fan speed, circumventing automatic control from the amplifier and temp sensors. Since defrost mode isn't working correctly it suggests that you have problems not related to the amplifier.
The first step is to understand how it is supposed to be, the second thing is understand how your car is wired and setup, the third thing is to fix it.
Jeff
I agree.
Most previous-owner, DIY wiring modifications are easy to spot and trace. Hopefully that holds true in this case
Hi
I just wanted to thank everyone for their help. I sent my post before I went to bed hoping to get something to ponder during the week before I worked more on my car next weekend. I woke this morning and saw all the posts. Thank you very much.
I really don’t know too much about my car’s past; other than around 2009 it was registered as a wedding car ( it is old English white colour ). The aircon has been upgraded to R134a but is out of gas. I’ve not gotten around to repairing the air con.
I suspect ampfier may have been done then too.
As a process of elimination only i will start with engine thermostat for the simple reason it stopped working after I changed it. A couple of the times in the past I shut of the heater valve ( it is not a vacuum one ) and climate control acted a bit funny. Then will try to figure out wiring.
Those videos are great. I was surprised to see how large the Delanair unit is. It seems there would be plenty of room where that came out of to pop in a complete Vintage Air system and be done with it. There was a recent post about installing one in a series 1 or 2 and that seemed to indicate it was a tight fit.
In defrost mode the system defaults to max heat and max fan speed, circumventing automatic control from the amplifier and temp sensors. Since defrost mode isn't working correctly it suggests that you have problems not related to the amplifier.
Cheers
DD
Doug,
Just a point to note...when you switch the mode control to defrost...you introduce a 27K Ohm resistance into the sensing circuit..biasing the system..which causes the amplifier to drive the servo to full heat...he may very well have an amplifier problem.
With the system powered on...the fans should run at low speed at a minimum. The fact the speed is intermittent...suggests to me a power issue to the fan relay. Either in the relay or the power switch on the mode control...could be a lose securing bolt..seen that a couple times.
Disconnecting the vacuum water valve could introduce a vacuum leak into the climate control system. Suggest correcting the hot water valve.
Must conduct systematic diagnostics to prove what works and what doesn't.
09-02-2018, 01:41 AM
XJ6 Series 3 - Heater/Air Con problem
