pacman777

Hey! I just figured out that the board burnt when it was not on defrost, but on top vent position. ??? If i get a new/rebuilt control head from Precision or Roger will it get fried too?

Alan

Pin 1 is the control line for the Footwell solenoid (the airflap vacuum pod).

Pin 6 is the AC clutch solenoid feed from the HVAC relay.

Are you sure this is the correct HVAC headunit for this car? did it ever work correctly?

Just for grins - does the car shut off when DEF is off but AC is On?

Reason I ask is that one of the things DEF does is turn on the AC - and you have something burnt up (pin 6) on the AC feed.

Will the car stop normally without DEF relay VIII
Will the car stop normally without Fresh Air Blower Relay X

Alan

pacman777

Will the ignition still work without relay x?

pacman777

Hi Alan. I pulled out relay x and the car has a delayed shut down. I put it back in and it is again a delayed shutdown instead of no shutdown. The car starts, runs, fan blows without relay x and delays shut down even on defrost. Delay is about 2 seconds. Same result with the defrost relay.

pacman777

Never had a problem with the hvac system before this. Everything worked. It all started when the car would not start and i swapped starter relay. Could it be the new hella relays i am replacing with?

pacman777

Old symptom of car not shutting off at all to car has delayed shutoff since pulling relay and putting back in. I even tried a good porsche relay 53 and same delay.

Hilton

Just a wild idea. Try pulling out the Rear Defroster relay (double-width one in bottom left of panel).

I haven't checked the wiring diagram to see if its electrically related to the HVAC defrost function, but even if not its possible that you have a separate unrelated fault in the rear demister circuit which is causing this symptom (a bad rear demister relay or stuck-in demister switch will cause the not-shutting-off symptom, and there's a timer in the relay).

pacman777

Hi Hilton. Thanks. Just tried removing rear defrost relay and still the same delayed shutdown.

pacman777

Does anyone think the car is safe to drive? And will a new head unit burn out as well?

Alan

Likely a new one will do the same thing without a fix.... you need more investigations - too expensive to risk frying another one...

I'd test the resistance on pin 1 without the head unit connected - to ground. What is the Ohms reading?

I still suspect the relay work you did - when did the continuing "run-on" start - just after the HVAC change or at some other point in your repairs?

What else did you work on shortly before this issues ocurred? any other changes to anything?

Are you sure the behaviour has really changed since you removed & reinstalled the relays? It should not have - that makes little sense to me...

Can you photograph the CE panel from the front so I can see what relays you have where...

Alan

pacman777

1. Car won't start. Changed relay x and starter relay, car starts. 2. Blower stops working. Replaced blower from Roger. Blower still not working. 3. Do gruner 970 fix. Blower works but fuse#8 blows constantly. 4. Change ignition. Fuse #8 no longer blows but won't shutdown unless defrost is turned off. 5. Rechecked relay location. all correct, tested no freeze switch, resistor pack. All good. 6. Found new burn on pin 1&6 line, but everything still works. 7. After testing without relay x, then defroster relay, and then rear defrost relay. No shutdown fixed but now delayed shutdown on all three tests.Really hoping a relay is in the wrong spot. Will send a pic when the kid comes home with a smart phone, only have a dumb phone, lol

Alan

OK terminology Qn: - X Relay and Relay in position X are totally different things - which are you talking about in this context?

Relay in Position X is the Fresh Air Bower Relay (for your year) - Blower & HVAC require this.

X- relay is in position IV (for your year) - X-Relay repeats the X-Bus (accessory Bus) from the Ignition switch (this is not critical to run, but can affect HVAC).

DEF relay in position VIII - causes the bower to run on high - thats all

Do Check (swap) the EZF Relay in position XVI (this can affect running)

Do Check (swap) the LH Relay in position XXV (this can affect running)

The head unit relay you swapped (Gruner) has nothing to do with the blower - it only affects AC
- changing this relay is NOT what made the blower work - it was something else...

It may however be what causes the fuse to blow... due to something wrong...

Alan

pacman777

Here is a picture of my panel.

pacman777

Thanks Alan, relay x is ignition relay x & relay in position x I will refer to as blower relay. I was refering to ignition relay as relay x , although both were changed because I swaped all the 53's with new Hellas. EZF & LH are no longer part of the equation because car has been converted to MegaSquirt, but were replaced with new ones anyways because all 53's were changed to new.

Alan

OK - that's a rather significant little snippet there...

So what is required to make the engine run with a MegaSquirt? Important question...

Just Ignition (15) OR does it actually have other relays driving it (e.g. re-purposed LH/EZF Relays).

BTW seems you have a lot of circuits that are rather important to driving the car without fuses installed...

I'm beginning to think this car has had a lot of work done...

Alan