My AC burns me up --- Summary of fix

[Discseven]

Originally Posted by GH85Carrera

I have had the driving conditions of driving at night so the heat load was low. The temp gets cold inside the cabin and my wife gets cold. I just pull the heater handle up on her side. With my El Camino if I get cold and turn the temp lever up it will indeed add heat even in the A/C mode. On a 911 like yours the heat and AC will run at the same time no problem.

LOL Glen! I get what you're saying... but... I've not touched my heater levers since the beginning of time. To do so would surly be another fix --- imagine... after all this, the heater stuck in ON position

[Discseven]

Closer look at resistor pak removed from plastic duct.




Shunts...




Will take stab at this and say one shunt gap is too open, other is too tight. Am thinking to make both gaps 3/64." Anyone suggest different measure?

Nice shunt note Will. These are very difficult to see when pak is attached to duct. TY

[Discseven]

Gaped both shunts equally (3/64"). Lightly lubricated and cleaned metal with WD-40. Installed & connected. Ran AC for about 10 minutes at different fan speeds... mostly low. Watched WD smoke off---coils do get hot. Success = zero jump from low to medium speed.




Seemed t-switch was more functional now in that it cut off when turned full CCW. Tested that a few times with same results. Next test = run t-switch at 75% to see response. Now, almost to point where I've nothing more complain about*...

Godzilla will be pleased.

* I'll find something.

[wwest]

Originally Posted by Discseven

TY for input. Going to get resistor now for closer look.

Not to hammer back on you Will... but for added detail, in this case the transition from low to medium speed on the low setting can be within seconds of starting the AC---so evap temp would seem to have no relationship to anomaly here.

Testing various temps on resistor while it is removed but still plugged in is in order. Based on what your saying, if I keep it cool... it should not jump speed. Will post results later.

Blower motor bearings may be in the process of failing...

You asked about a noise coming from the A/C....

Squirrel cage blower wheel rubbing?

[Discseven]

Originally Posted by wwest

Blower motor bearings may be in the process of failing...

You asked about a noise coming from the A/C....

Squirrel cage blower wheel rubbing?

Blower and cage---yeah, been thinking about that but clearance was checked when connecting blower. Sound is very tinny with an open resonance so not like bearings. Capillary drumming evap... that seems the sound. Will check all after breakfast.

[wwest]

Puzzle..


When in low speed both resistors are in the circuit, in series. Should one of them overheat and thereby cause it's associated thermostatic switch to close the blower speed will increase.

But....

With the thermostatic switch closed the resistor will/would cool to the point that the closed switch should open and the speed should retard. A cycle back and forth should ensue.

The only possible explanation I can come up with is that once the thermostatic switch closes it sticks closed.

File/burnish the contacts so the contact surface is smooth..?


Or did adjusting the gap solve the problem?

[wwest]

I would suggest that the blower motor is connected backward resulting a low airflow, but at the same time with it turning backwards less "work" is being done resulting in a lower current flow for the motor, less heating of the resistors.

The alternate explanation. Carpet, etc, is so seriously blocking passenger inlet side flow that most of the system air flow is via the driver's side.

Then again... With that one contact gap being so narrow it may be being closed partially from the heat radiating from the opposite resistor. It then closes resulting in more heating of the opposite resistor thereby keeping it closed indefinitely.

So adjusting the gap may well have resolved the issue.

[Discseven]

Originally Posted by wwest

Puzzle..


When in low speed both resistors are in the circuit, in series. Should one of them overheat and thereby cause it's associated thermostatic switch to close the blower speed will increase.

But....

With the thermostatic switch closed the resistor will/would cool to the point that the closed switch should open and the speed should retard. A cycle back and forth should ensue.

The only possible explanation I can come up with is that once the thermostatic switch closes it sticks closed.

File/burnish the contacts so the contact surface is smooth..?


Or did adjusting the gap solve the problem?

These coils heat up nearly instantly. I suspect that given the nearly closed contact, the immediate heat was causing the shunt to close and so the jump from low to medium a few seconds after starting AC.

Drove for an hour today and no jump from low to medium. Had 1 surprising jump from medium to high... that's NEW. I failed to look at shunts with AC on and resistor out so did not check to see how far they move when coils get hot. Might be they need a greater gap than 3/64." Will sand contacts when resistor is pulled---good idea Will. TY again for shunt note.

Have not gotten to "noise" yet as planned. Will see about attending in the afternoon.

[Discseven]

Originally Posted by wwest

I would suggest that the blower motor is connected backward resulting a low airflow, but at the same time with it turning backwards less "work" is being done resulting in a lower current flow for the motor, less heating of the resistors.

The alternate explanation. Carpet, etc, is so seriously blocking passenger inlet side flow that most of the system air flow is via the driver's side.

Then again... With that one contact gap being so narrow it may be being closed partially from the heat radiating from the opposite resistor. It then closes resulting in more heating of the opposite resistor thereby keeping it closed indefinitely.

So adjusting the gap may well have resolved the issue.

Now you've lost your marbles. After all this... how can you can imagine my connecting the blower backwards?! That said, I do appreciate your thinking about it.

Carpeting. Seems innocuous. But now I realize how important the intake area is and how the carpeting needs to be configured correctly to allow air to easily enter system. It's well configured. And I'm not the dirty bohemian I once was. Evap is going to stay clean now.

[wwest]

Originally Posted by Discseven

Now you've lost your marbles. After all this... how can you can imagine my connecting the blower backwards?! That said, I do appreciate your thinking about it.

Looking in the bottom of the bucket for anything that would result in airflow so low as to allow the resistor(s) to overheat. Note that it was expressed as a passing thought, not a possible action item.

Carpeting. Seems innocuous. But now I realize how important the intake area is and how the carpeting needs to be configured correctly to allow air to easily enter system. It's well configured. And I'm not the dirty bohemian I once was. Evap is going to stay clean now.

[wwest]

Originally Posted by Discseven

These coils heat up nearly instantly. I suspect that given the nearly closed contact, the immediate heat was causing the shunt to close and so the jump from low to medium a few seconds after starting AC.

Drove for an hour today and no jump from low to medium. Had 1 surprising jump from medium to high... that's NEW. I failed to look at shunts with AC on and resistor out so did not check to see how far they move when coils get hot. Might be they need a greater gap than 3/64." Will sand contacts when resistor is pulled---good idea Will. TY again for shunt note.

Have not gotten to "noise" yet as planned. Will see about attending in the afternoon.

Very fine emery...

[Ronnie's.930]

Karl, the odd noise you describe, as well as the phantom fan speed switcharoos, are likely signs of the previously (many times) mentioned "black death" rearing its ugly head at long last! Have you checked the switch contact points for fines?

[Discseven]

Originally Posted by Ronnie's.930

Karl, the odd noise you describe, as well as the phantom fan speed switcharoos, are likely signs of the previously (many times) mentioned "black death" rearing its ugly head at long last! Have you checked the switch contact points for fines?

F'in Ron... good thing you're wearing sarcasmo green. Very clever. Tread lightly in THIS THREAD, or am coming after you with multitude of angry tattooed biker chicks... who want to vent in a bad way.

Get technical MONSTER... post your 29.5 dF evac & gas charge method. Or pull popsicle out of your duct.

[wwest]

Fully air conditioned...

[Discseven]

Originally Posted by wwest

Fully air conditioned...

Nice... where is that?

[wwest]

Originally Posted by Discseven

Nice... where is that?

Not sure, been awhile..

Either Long Beach Wa, or Cannon Beach Oregon.

1978 Targa, coming home from Boise Monday.

[Discseven]

Took a look at shunts in action. This is with fan speed on low, t-switch full CCW, and resistor out of duct. Takes a few seconds for thin coil shunt to close once AC is turned on. Bear in mind there's no air passing over this to cool it.



Also looked at speed 2 and 3. Shunts did not move. Opened both gaps to just over 1/16" and cleaned contacts with emery. Have no idea if this gap is on, off, or near spec. Will see how it works.

Next on today's menu is hunt for vibration coming from evap area. Is noticeable on speed 2 at idle only (as in stopped at red light). Not noticeable when driving due to drive noise. Speed 1 is fine. Speed 3 there's too much air noise from vent to hear it.

Took blower housing off - (camera battery dead now) and checked to make sure it was blowing in right direction . Yes. Checked clearance again. OK. Ran at different speeds... it's quiet. Picked up housing when running... and... Unbalanced blower. Missing this fact when checking the motor spin (without touching it) on prior install is error to be added to list.

Even with potential problem found, thermo probe in core of evap is isolated from evap as capillary travels from core to exit of plenum, harder stand offs are placed between blower housing and evap, capillary is isolated from outside of plenum as it travels toward cabin. Idea being to squelch vibrations coming from any of these parts/areas.

Result - Vibration noise is... much worse now!

Next move - Hunt for balanced blower.

[Ronnie's.930]

Originally Posted by Discseven

Tread lightly in THIS THREAD, or am coming after you with multitude of angry tattooed biker chicks... who want to vent in a bad way.

Like her for example? Promises promises, Karl (you tease)!!!

Originally Posted by Discseven

Next move - Hunt for balanced blower.

Cornstarch sez that to find one of those in his neck of the woods, one must troll the local watering holes with a corncob tied to a string!

[wwest]

Originally Posted by Discseven

Took a look at shunts in action. This is with fan speed on low, t-switch full CCW, and resistor out of duct. Takes a few seconds for thin sping shunt to close once AC is turned on. Bear in mind there's no air passing over this to cool it.



Also looked at speed 2 and 3. Shunts did not move. Opened both gaps to just over 1/16" and cleaned contacts with emery. Have no idea if this gap is on, off, or near spec. Will see how it works.

Next on today's menu is hunt for vibration coming from evap area. Is noticeable on speed 2 at idle only (as in stopped at red light). Not noticeable when driving due to drive noise. Speed 1 is fine. Speed 3 there's too much air noise from vent to hear it.

Took blower housing off - (camera battery dead now) and checked to make sure it was blowing in right direction . Yes. Checked clearance again. OK. Ran at different speeds... it's quiet. Picked up housing when running... and... Unbalanced blower. Missing this fact when checking the motor spin (without touching it) on prior install is error to be added to list.

Even with potential problem found, thermo probe in core of evap is isolated from evap as capillary travels from core to exit of plenum, harder stand offs are placed between blower housing and evap, capillary is isolated from outside of plenum as it travels toward cabin. Idea being to squelch vibrations coming from any of these parts/areas.

Result - Vibration noise is... much worse now!

Next move - Hunt for balanced blower.

I would wager on a bent motor shaft first.

Clamp the motor in a soft wood jawed bench vise, power it, and use a piece of chalk to see if, how much, the wheel wobbles.

If the wheel actually is out of balance you can experiment with placing weights at different points rotationally using that same bench vise technique.

If you end up in the market you might want to see if the later motor/wheel will fit, seems to have had more design effort go into it.

[Discseven]

Originally Posted by Ronnie's.930

Like her for example? Promises promises, Karl (you tease)!!!

Cornstarch sez that to find one of those in his neck of the woods, one must troll the local watering holes with a corncob tied to a string!

That's beauty pageant BC your picking out Ronster. I'm talking sewer sleeping, worm eatin, wear same leather all your life biker chicks---nothing like your delusion. More like what Corn's referring to. That said, rules of engagement require we delete our off topic posts. You first.