A/C only works when driving!?

[WFO]

Sorry for posting and ghosting.
But I couldn't replicate the problem until yesterday. It was the first really hot day since that day in May when it first happened that I had a chance to drive it. I turned the A/C on as I left my driveway. Got down to the end of the street and it's like I flipped a switch and shut it off. I tried it on all the setting (low, medium, high) and nothing came out of the vents. But as soon as I hit the gas to leave the intersection, the air came back on and was blowing cold. And it operated fine a few mins later when I came to a stop a couple times at the end of that drive.

But then today, it worked just fine leaving the neighborhood and arriving at my destination.

It is my daily, but that's very relative since I work from home and only need to drive it 2-3x a week. So I kinda feel fine about it - in that it appears to work most of the time. But at the same time, it's clearly got something wrong, but what??

Are you hooked up to manifold vacuum or ported vacuum? Ported won't operate the diverter door at idle.

 

[RaysnCayne]

Are you hooked up to manifold vacuum or ported vacuum? Ported won't operate the diverter door at idle.

I think it's manifold? (See photo attached. The line from the firewall eventually ends up at that vacuum port tree in the manifold.)

And now that you mention vacuum to this system, this is an area where I had to "guess" when I (sort of) restored the engine bay a couple years ago. So maybe I've messed something up with the vacuum line routing?
The plastic "hardline" hose coming out of the firewall was damaged a bit, so I had to cut a few inches off. But I'm pretty sure it went into that clear connector. Which went into that "T", which went down into a two-way vacuum tee fitting that I believe was capped on one side. But a lot of this was a guess based on the heavily-deteriorated original lines that were there. So by all means, if you see where I've gotten something backwards or flat out wrong, please LMK.

 

[Radiohead]

Dumb thought here, but is what's being described a low voltage at idle issue, where when he accelerates the alternator output increases and the fan starts turning perceptively? Not that improper vacuum source is not a problem, but it's weird as described, no?

 

[gmbellew]

not sure if the OP has specified if the blower stops or just the airflow out of the vent stops. also, try the blower on high because that bypasses the relay.

 

[RaysnCayne]

not sure if the OP has specified if the blower stops or just the airflow out of the vent stops. also, try the blower on high because that bypasses the relay.

Everything stops. I moved the fan speed through all the ranges when it happened and nothing worked.

Radiohead: A friend riding with me just this past weekend mentioned alternator deficiency as a possible cause. So I'll see if I can figure out how to test its output in operating conditions.

 

[Ricko1966]

Everything stops. I moved the fan speed through all the ranges when it happened and nothing worked.

Radiohead: A friend riding with me just this past weekend mentioned alternator deficiency as a possible cause. So I'll see if I can figure out how to test its output in operating conditions.

Did you ever check blower motor operation as mentioned. You've been told before your hiatus things to check,we never got any answers. If I could be there to verify,I'd bet you money it's not the alternator. You need to verify if the blower motor quits running or air just quits coming out of the dash vents.

 

[WFO]

I think it's manifold? (See photo attached. The line from the firewall eventually ends up at that vacuum port tree in the manifold.)

And now that you mention vacuum to this system, this is an area where I had to "guess" when I (sort of) restored the engine bay a couple years ago. So maybe I've messed something up with the vacuum line routing?
The plastic "hardline" hose coming out of the firewall was damaged a bit, so I had to cut a few inches off. But I'm pretty sure it went into that clear connector. Which went into that "T", which went down into a two-way vacuum tee fitting that I believe was capped on one side. But a lot of this was a guess based on the heavily-deteriorated original lines that were there. So by all means, if you see where I've gotten something backwards or flat out wrong, please LMK.

What I can see looks good, but I can't see where the end of the vacuum hose hooks up.
Plus I'm not too familiar with fuel injection.

As others have stated, if the fan isn't blowing, I'd start looking for the problem there.

 

[gmbellew]

I think it's manifold? (See photo attached. The line from the firewall eventually ends up at that vacuum port tree in the manifold.)

And now that you mention vacuum to this system, this is an area where I had to "guess" when I (sort of) restored the engine bay a couple years ago. So maybe I've messed something up with the vacuum line routing?
The plastic "hardline" hose coming out of the firewall was damaged a bit, so I had to cut a few inches off. But I'm pretty sure it went into that clear connector. Which went into that "T", which went down into a two-way vacuum tee fitting that I believe was capped on one side. But a lot of this was a guess based on the heavily-deteriorated original lines that were there. So by all means, if you see where I've gotten something backwards or flat out wrong, please LMK.

Are you missing the vac line that goes to the vacuum reservoir off of that T just downstream of the check valve. I dont recall my setup having a plugged T there. Or does the other line off the other T head that direction to the reservoir? Vac should be good at idle, though.....so I'd expect that to cause more issues in low vac driving situations.

 

[RaysnCayne]

Did you ever check blower motor operation as mentioned. You've been told before your hiatus things to check,we never got any answers. If I could be there to verify,I'd bet you money it's not the alternator. You need to verify if the blower motor quits running or air just quits coming out of the dash vents.

@Ricko1966
I just ran through the fan settings to check.

A/C mode: Works in high. Works one notch below high.
Vent mode: Works in high. Works one notch below high.
Heat mode: Nothing out of the dash vents at all on high or one notch below (or any notch below that). But good, strong airflow from under the dash and medium airflow at the defrost vents. Is that cause for concern? Or is that the default outlet for heat?

@gmbellew
Yep. I got a new, clean hose from the "T" at the clear connector over to the vacuum ball on the driver's side.

 

[Ricko1966]

So the blower motor is working,you need to verify it is working still when the AC quits blowing. If the blower is running but not blowing air it's a blend door issue probably vacuum to control unit. If it were an actual AC problem it would still blow it would just blow warm air. Think of it like a fan on a window.
If you unplug the fan air quits blowing.

If you shut the window in between you and the fan,air quits blowing on you.

Be sure the blower motor itself always runs,if so you have a blend door closing shutting off or redirecting airflow.

 

[gmbellew]

Air is coming from the right places on those settings

 

[RaysnCayne]

you need to verify it is working still when the AC quits blowing. If the blower is running but not blowing air it's a blend door issue probably vacuum to control unit.

On the last time it stopped working, I flipped through all the fan speed settings and was getting absolutely nothing out of the vents, no warm air, nothing.
Maybe that means I have a blower motor on the way out?

 

[gmbellew]

On the last time it stopped working, I flipped through all the fan speed settings and was getting absolutely nothing out of the vents, no warm air, nothing.
Maybe that means I have a blower motor on the way out?

It sounds like it is likely electrical, and could be the motor or an alternator issue. But next time try to see if you can get under the hood and check the actual motor to make sure it is not doing anything vs just feeling at the vents

 

[Ricko1966]

On the last time it stopped working, I flipped through all the fan speed settings and was getting absolutely nothing out of the vents, no warm air, nothing.
Maybe that means I have a blower motor on the way out?

Okay let's try to make this dirt simple. Verify if the blower motor us running,get under the hood and check. The blower motor OR a blend door will stop air flow, an AC problem will create warm air. Remember my scenario above? If you unplug a fan,it quits blowing on you,but if you close a windoe between you and a fan it also will quit blowing on you.

 

[RaysnCayne]

Sorry I'm so dense guys. (Really appreciate you stickin' with me and trying to help this very A/C-ignorant fella out!)
The blower motor is attached to the "squirrel cage" fan thing that's bolted into the big housing on the firewall just behind my pass. side inner fender? Since it's fully encased, how would I be able to actually see if it's turning? Will I feel it running through the case?