Max AC always works, Normal AC hit or miss

[orbitron3000]

I am having an interesting problem with the AC system on my car. No matter what the condition, when I turn on the Max AC, it always works and is ice cold. But when I turn it to the normal AC, it's hit or miss on whether or not anything comes out of the vents. It's like the fans just stop blowing on normal AC. The fans will blow on vent, heat, defrost, and max AC. My first thought is maybe a relay that's on the fritz. Is this a good place to start? Where else could the problem be?

Thanks.

[Bitsyncmaster]

Do you mean the amount of air coming out of the vents changes from Max to Norm? Does it do it with a door or window open? If not then your car is sealed up to tight.

That would have to be a problem with the mode switch.

There are no electrical differences switching from Max to Norm.

[orbitron3000]

Yes, on Max the air flows normally, but on normal, sometimes no air comes out regardless of the fan speed. Sometimes it'll work just fine on normal, and on max the fans sound like they're going a little harder, but mostly on normal ac, nothing comes out of the vents.

[stevedmc]

Yes, on Max the air flows normally, but on normal, sometimes no air comes out regardless of the fan speed. Sometimes it'll work just fine on normal, and on max the fans sound like they're going a little harder, but mostly on normal ac, nothing comes out of the vents.

Has your AC switch ever been rebuilt? Does it make any hissing noises? You could be experiencing a leak in the switch. I would get on the phone with your vendor of choice to see about having it rebuilt. I think Hervey rebuilt mine for about $35.

[orbitron3000]

There is a hissing noise when I go from either of the AC's to the vent. I'm not sure if it's even been rebuilt. Would it be a difficult procedure to rebuild the switch on my own?

[DeLorean03]

I have had this problem the entire time I've owned my car. Let me guess - you don't have "Heater" too ? I have wondered for so long what this is. I have the mode switch diaphragm here ready to rebuild. Hope the Ohio DeLorean Club is ready ;).

And yep - mine hisses too.

[stevedmc]

The switch isn't supposed to hiss. Rebuild the thing and the problems should go away, unless there is something else that is broke.

Basically there is a rubber diaphram that needs to be replaced. It is pretty simple to do but I decided to let Hervey rebuild it. I'm not sure what DMCH sells the part for but they do have detailed instructions on their support site if you choose to use their part.

www.delorean.com/pdf/modeswitch-rebuild.pdf

[orbitron3000]

I have had this problem the entire time I've owned my car. Let me guess - you don't have "Heater" too ? I have wondered for so long what this is. I have the mode switch diaphragm here ready to rebuild. Hope the Ohio DeLorean Club is ready ;).

And yep - mine hisses too.

I seem to have all modes, except for "Normal AC" (I had to go and look -- never used the heater before :histerical1:)


The switch isn't supposed to hiss. Rebuild the thing and the problems should go away, unless there is something else that is broke.

Basically there is a rubber diaphram that needs to be replaced. It is pretty simple to do but I decided to let Hervey rebuild it. I'm not sure what DMCH sells the part for but they do have detailed instructions on their support site if you choose to use their part.

www.delorean.com/pdf/modeswitch-rebuild.pdf

Awesome, thanks!

[sean]

The switch isn't supposed to hiss. Rebuild the thing and the problems should go away, unless there is something else that is broke.

Basically there is a rubber diaphram that needs to be replaced. It is pretty simple to do but I decided to let Hervey rebuild it. I'm not sure what DMCH sells the part for but they do have detailed instructions on their support site if you choose to use their part.

www.delorean.com/pdf/modeswitch-rebuild.pdf
:icon_smile_duh:

Top Roman Steve aint stupid but that was the closest thing to a "what he said" smiley I could find....;)

[DavidProehl]

May not be relavant, but I had a similar issue when I first bought my car with my heat not working (no fans, nothing). Turned out a couple wires had swapped locations behind the control unit. When I verified and properly hooked up my wires to the right locations, my heater then worked. Perhaps something similar could happen with the A/C?

[content22207]

Like most cars of their era, DeLoreans use vacuum to operate various HVAC ductwork flaps (outside air, face level vents, floor vents, etc). The mode switch routes vacuum to the diaphragms that open and close these flaps. It also switches electricity to the A/C compressor and the blower motor. Page N:08:15 of the Workshop Manual has two charts that show what is activated at various mode switch positions.

The only differences between Max and Normal A/C:
- Outside air flap is closed for Max, open for Normal
- Heater core water is closed for Max, open for Normal
Otherwise flap actuation and blower motor operation should be identical between them.

The temperature control knob moves a cable that opens and closes the HVAC ductwork flap over the heater core.

Bill Robertson
#5939

[Ron]

It might be worth noting that it is normal for the mode switch to momentarily make a hissing sound immediately after changing modes (depending on the selection) while it vents diaphragm(s).
The younger you are, the louder it will sound :)

[john 05141]

Well well,I had the EXACT same thing last year. I just could not figure this out, no logic.
It happened the first time while I was driving on the highway, and I could not hear the wind from the vents, but felt the car heating up.

So later on standing still, I noticed ony the max AC worked :confused:

As I usually deal with those things in the winter time, I did not bother to look at it right away as I had a werking AC.

But as problems have dissapeared before by itself on my car, It did so again this time.... Spooky....:doorpeek:

John

[stevedmc]

:icon_smile_duh:

Top Roman Steve aint stupid but that was the closest thing to a "what he said" smiley I could find....;)

Thats pretty bad when the site admin can't even navigate the new smiley menu.

[sean]

Thats pretty bad when the site admin can't even navigate the new smiley menu.

Oh, I can navigate, I just don't think we have it. Im liking the "Im with stupid" even more now. :D

[orbitron3000]

So last week I installed the new "rebuilt" switch kit. As far as I can tell, the car will switch each mode properly with an occasional hiss between modes.

However, no matter what I try, the vents in the center console will not open. I have put the car in Max AC and turned the fan speed to four as per the instructions, but nothing doing. Is there some step that I am missing? Another failure point (like a vacuum leak or something along those lines)? The side vents and floor vents still work as they should.

[DMCMW Dave]

The arm breaks off the actuator. Usually caused by a car stereo installer. The actuator is just to the left of the glove box.

[jawn101]

The switch isn't supposed to hiss. Rebuild the thing and the problems should go away, unless there is something else that is broke.

Basically there is a rubber diaphram that needs to be replaced. It is pretty simple to do but I decided to let Hervey rebuild it. I'm not sure what DMCH sells the part for but they do have detailed instructions on their support site if you choose to use their part.

www.delorean.com/pdf/modeswitch-rebuild.pdf

Mine only hisses when switching between modes. For example, A/C to Off - there will be a low clunk as the doors close, and a moment of "pssshhh". No noise when the system is operating or turned off. Is this abnormal?

*EDIT* just saw Ron's post above. Guess this is normal as long as you're not a young'un like me :)

[orbitron3000]

The arm breaks off the actuator. Usually caused by a car stereo installer. The actuator is just to the left of the glove box.

What should the actuator arm look like? Where is it on the diagram? I can't seem to find it.

[DMC5180]

The Vacuum actuator and arm assembly is located just left of the glovebox insert. You can probably see it with a flashlight if you can get your head under there.

It opens and closes the center ducts.

I tried posting a link to the delorean.com parts page. but something is not working right I could not get past the sections list.

[orbitron3000]

The Vacuum actuator and arm assembly is located just left of the glovebox insert. You can probably see it with a flashlight if you can get your head under there.

It opens and closes the center ducts.

I tried posting a link to the delorean.com parts page. but something is not working right I could not get past the sections list.

Taking a stab here: http://www.delorean.com/store/p-7633-air-inlet-assy.aspx

Is this the piece where the control arm in question is?

[DMC5180]

No. that's the max A/C recycle air door.

This is the part assembly http://www.delorean.com/store/p-7624-housing-air-dist.aspx

The picture is upside down from the way it is installed. The arm is attached to the vacuum actuator. It is only available as part of this assembly. so if you were to need one you would have to buy this whole unit.

[orbitron3000]

No. that's the max A/C recycle air door.

This is the part assembly http://www.delorean.com/store/p-7624-housing-air-dist.aspx

The picture is upside down from the way it is installed. The arm is attached to the vacuum actuator. It is only available as part of this assembly. so if you were to need one you would have to buy this whole unit.

Thanks! Gonna go check this out.

[orbitron3000]

So the assembly appears to be intact. I can manually move the arm to open and close the vacuum vents. For some reason it always defaults to closed and wont stay open. What could be wrong?

Ryan
#5780

[orbitron3000]

Upon digging a little deeper behind the console, I've found what I am hoping is the culprit. It looks like a vacuum hose may have come unplugged. However I don't know where it plugs into. http://tapatalk.com/mu/aeff273c-2213-7cbc.jpg

Ryan
#5780

[orbitron3000]

I think I need to wait like 5 minutes more before posting because I seem to keep answering my own questions if I look hard enough. I managed to find where this mystery tube came from. Once I plugged it in, the arm opened and closed the vents as I switched modes. Now it only seems to open the face level vents on Max AC so I'm hoping that I just need to switch some wires on the mode selector and it'll all be fixed.

Ryan
#5780

[orbitron3000]

Well, I switched the wires around and still only the Max AC puts air out of the face level vents. Any idea why when Normal AC, Bi Level, and Vent are selected it closes the face level vents?

[Ron]

Swap the orange and red vacuum lines on the back of the mode switch.

[orbitron3000]

Swap the orange and red wires on the back of the mode switch.

I don't have separate orange and red wires. I have Solid Green, Pink-Orange in the middle, and then Light Green-White wire. I have swapped the Solid Green and the LGW wire. What wires are you referring to?

[Ron]

No hoses!
you caught me during and edit..I was faster than the clock but not you lol

[orbitron3000]

No hoses!

Well now I feel very dumb. Reading is apparently not one of my strong suits...sorry about that.

[Ron]

Not dumb...fast LOL
You caught me before I corrected myself...and then you got on this page before I could tell you and missed that too.

I'm going to delete this and previous message when we get together. LMAO

[orbitron3000]

not dumb...fast lol
you caught me before i corrected myself...and then you got on this page before i could tell you and missed that too.

I'm going to delete this and previous message when we get together. Lmao

hahahaha

[Ron]

Dang, you havent tried it yet, Speedy?

[orbitron3000]

Dang, you havent tried it yet, Speedy?

Not quite yet. Though I am excited to get it working.

[orbitron3000]

Swap the orange and red vacuum lines on the back of the mode switch.

There are two oranges. A thin orange stripe and a thicker orange stripe. Which one should I swap with red?

Ryan
#5780

[Ron]

I think no stripe..I forget...But it is the one that is NOT the supply. I would think it would be the same size as the red one...

What I think is going on is that you have the Top Mode-Face Level swapped with the Recirculation-Water lines.

[orbitron3000]

I think no stripe..I forget...But it is the one that is NOT the supply. I would think it would be the same size as the red one...

What I think is going on is that you have the Top Mode-Face Level swapped with the Recirculation-Water lines.

H'm. Its just strange because all the vents were switching and working normally before I rebuilt the mode switch. It's then that I bumped out a vacuum line on the arm actuator assembly.

Ryan
#5780

[Ron]

Try it -- you'll like it!

(Can't hurt anything and easy enought to remember and put back)

(See why they say if it's not broke, don't fix it LOL...just kidding!)

[orbitron3000]

Gonna do it. Just looked it up in the workshop manual. Orange and red just like you said. Any tips for switching them? I'm pulling and twisting and pulling but they wont budge.

Ryan
#5780

[orbitron3000]

Nevermind. Just takes a swift Yank.

Ryan
#5780

[Ron]

Gonna do it. Just looked it up in the workshop manual. Orange and red just like you said. Any tips for switching them? I'm pulling and twisting and pulling but they wont budge.

Ryan
#5780 Not really...Infact that sounds odd to me because mine fell out...which is why I had to learn what they all did...

Look at the manual, the next page has a view with numbers that match 4 of the 5 colors and see if the order is like we expect...

[Ron]

nevermind. Just takes a swift yank.

Ryan
#5780OMG! :rofl:

[orbitron3000]

And it works! Thanks very much for your help!

Ryan
#5780

[Ron]

:thumbup: NP Been fun!!!!!!!!