My AC burns me up --- Summary of fix

[Discseven]

Originally Posted by wwest

I would wager on a bend motor shaft first.

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

Bent shaft... Hmmmm. Good idea to check that before getting new blower. TY Will.

Thought about attempting a balancing act but who knows how long that would take. Would rather spend a few dollars on a done deal. ...Something just occurred to me given balancing thoughts. There is what appears to be a weight on one of blower's blades...



Took this photo after cleaning blower many weeks ago. Fact that this "weight" is not centered in length of blade might be throwing balance off. Before anything else... am going to move this weight around on blade. We'll see what happens.

[wwest]

Originally Posted by Discseven

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.

[wwest]

Originally Posted by Discseven

Bent shaft... Hmmmm. Good idea to check that before getting new blower. TY Will.

Thought about attempting a balancing act but who knows how long that would take. Would rather spend a few dollars on a done deal. ...Something just occurred to me given balancing thoughts. There is what appears to be a weight on one of blower's blades...



Took this photo after cleaning blower many weeks ago. Fact that this "weight" is not centered in length of blade might be throwing balance off. Before anything else... am going to move this weight around on blade. We'll see what happens.

Did you remove the wheel from the motor shaft and how much effort was required?

Blower wheel backplate is easily bent IMO.

[wwest]

Gas furnace blower, note 2 balance weights.

Pressure washing the one on the right was a mistake, random paint removal put it completely out of balance.

It would appear that closer to the outer edge is a more proper/standard placement.

From an engineering aspect the furtherest from the motor bearing with weight clip only on the inside makes sense.

[Discseven]

Originally Posted by wwest

Did you remove the wheel from the motor shaft and how much effort was required?

Blower wheel backplate is easily bent IMO.

Yes... removed blower from motor shaft. Not easy. Let soak in penetrating but still had to pry off. Did notice flexibility of blower when on shaft. Am going to pull blower housing now.

Got it on toilet.

[Discseven]

Back into blower...

Tested weight in a few different positions. Finally removed it. No difference in vibration. (Put weight back in original position.)




Spinning blower slowly by hand, blower's outer rim is discovered off center by about 1/16." Bent it back as well as possible. Would have removed blower to check shaft but rivits retaining housing's teeth need to be drilled out to release cage --- lent drill out so there's no getting into cage today.




Fiddling around with motor... it's loose. On closer inspection, hard rubber standoffs on motor's retainer screws are worn down. So is plastic on cage where standoffs make contact. Fact that blower is not balanced (or not in balanced position), am thinking loose motor in cage might be making the noise.




Thinking about rotating rubbers to fresh position. Worn area is shinny spot near screw head, not large indent. (There's flat head screw driver slots in motor's retainer screws but they're useless when motor's in cage. Tiny adjustable wrench works here.)




Dropped rotation idea. Put metal standoffs on both sides. Will still look at shaft and possibly replace blower to eliminate vibration. Don't like idea of leaving metal standoffs on plastic without getting rid of whatever is causing vibration.




Vibration noise = gone.

[kuehl]

9 times out of 10 you can 'balance' the geometry of the blower wheel; the perpendicularity of the shaft hub to the wheel disk it is attached to; usually it becomes cocked over time or when someone bends is "accidentally". What you do is mount the wheel on the motor shaft, the motor remains fixed in its plastic motor plate. Level the plastic plate and take a dial indicator touching the wheel disk near its top outer circumference. Slowly rotate the blower wheel and locate the highest point of wobble (use a pencil), then gently bend down (a few inch pounds of force) on the blower wheel at this point. Again rotate the wheel and repeat the procedure until you get no more than .005" of total indicator movement. Be careful not to bend the hub too much as it is pressed & rolled into a hole in the top plate

You will not be able to easily correct the geometry, of say, an 'egg' shape, such if you dropped the blower wheel on the ground and distorted its round shape; you would need to eye ball that one or again use an indicator and rotate the wheel while it was affixed to straight shaft on v blocks.

Leave the weight clips where you found them. The early metal wheels were made by a Torrington Division, they used a dynamic wheel balancer alike what is used to balance a turbine; not cheap equipment.

[Discseven]

Originally Posted by kuehl

9 times out of 10 you can 'balance' the geometry of the blower wheel; the perpendicularity of the shaft hub to the wheel disk it is attached to; usually it becomes cocked over time or when someone bends is "accidentally". What you do is mount the wheel on the motor shaft, the motor remains fixed in its plastic motor plate. Level the plastic plate and take a dial indicator touching the wheel disk near its top outer circumference. Slowly rotate the blower wheel and locate the highest point of wobble (use a pencil), then gently bend down (a few inch pounds of force) on the blower wheel at this point. Again rotate the wheel and repeat the procedure until you get no more than .005" of total indicator movement. Be careful not to bend the hub too much as it is pressed & rolled into a hole in the top plate

You will not be able to easily correct the geometry, of say, an 'egg' shape, such if you dropped the blower wheel on the ground and distorted its round shape; you would need to eye ball that one or again use an indicator and rotate the wheel while it was affixed to straight shaft on v blocks.

Leave the weight clips where you found them. The early metal wheels were made by a Torrington Division, they used a dynamic wheel balancer alike what is used to balance a turbine; not cheap equipment.

TY for info CG. Will "drill out" motor & blower today and make blower true. If vibration still there, will check shaft. Reason to drill out... Teeth butt plastic motor plate on two sides. Rivets must go to get plate out.

[ParkerFE]

Wow, how much would you charge to come to Atlanta and do what you did to my 88 cab a/c?

[kuehl]

Karl,

If you have a 1970-1985 Behr Evaporator Box....
This "screw & bushing" oddity attached to your evap blower motor assembly. Strange.
I'd guess someone added this because the motor was slipping in the round plastic housing. Occasionally when we work on clients cars of this era (1970-1985) we come across a round plastic housing that is cracked or broken, however most are quick fixed using a simple hose clamp. I'd say someone went a different avenue in trying to fix an issue where the evap motor was slipping through the round plastic housing.




The original factory design, to secure and hold the motor, inside the plastic motor support bracket, is simple: its a slip fit into the round plastic housing that is support by 4 plastic stanchions, and the motor is secured to that using 4 metal clips. There is a lip on the round plastic housing that "stops" the motor from moving all the way through; the round metal motor case sits against it.












3 images above compliments of MThomas58
Kuehl Hurricane Blower Motor Upgrade

[kuehl]

Originally Posted by ParkerFE

Wow, how much would you charge to come to Atlanta and do what you did to my 88 cab a/c?

What's the best golf course there?

[Discseven]

Originally Posted by ParkerFE

Wow, how much would you charge to come to Atlanta and do what you did to my 88 cab a/c?

I'd do it---love Atlanta. PM me if you're serious Parker.

[Discseven]

Originally Posted by kuehl

Karl,

If you have a 1970-1985 Behr Evaporator Box....
This "screw & bushing" oddity attached to your evap blower motor assembly. Strange.
I'd guess someone added this because the motor was slipping in the round plastic housing. Occasionally when we work on clients cars of this era (1970-1985) we come across a round plastic housing that is cracked or broken, however most are quick fixed using a simple hose clamp. I'd say someone went a different avenue in trying to fix an issue where the evap motor was slipping through the round plastic housing.

Agreed on mod CG. Soon as screw in metal housing came out... that raised WTF flag. But, config is functional so I modified on with it.


Back into blower...

Given number of round trips I've made into plenum, can now remove blower housing from evap box in less than 30 seconds. "Quick eject" config has come in very handy. Below is look at 12, 3, 6, and 9 o'clock measuring on hub side of blower. This side = on center.




Outer rim = off center. Adjustment done yesterday only moved blower slightly. Not surprising since hub cannot be moved much when blower's trapped in cage (as it was yesterday.) Rather than make adjustment with blower mounted to motor, am taking overcautious route... Have removed blower from motor and am holding it with drill bit. Then bending down on it lightly per CG. It goes back on center. TY Charlie.




Chalk is curious tool to test shaft's perpendicular with. Thought I had some stashed away from son's scribble-on-road days but nope. So, with motor on plate, plate clamped to work bench, and stationary caliper... am slowly turning shaft. Yeah, am guilty of stonehenging here with ass end of caliper but not going to get "smart tool" for this just yet. Shaft 'looks' good. To back up stonehenge caliper method, have turned AC on for a feel test. Motor running absent blower = damm smooth. Next is blower feel test. Impressive. Small adjustment just made has made big difference...



Vibration = gone. Now, everything goes back in place once more... and it's into cabin to check vent noise...

Holly f***... cold & quiet together.


Next is... t-switch test under operating conditions. Before doing this, will reload 26 oz dry hose liquid charge. Reason: test t-switch with optimal charge. Since thread 2 has been blown up, here's explanation so some sense might be made of what's going on: Optimal performing charge is version 6.1. Other versions of 6 (2-4) were done with increased refrigerant weights (28, 30, 32 ozs.) as shown below. Above 26 ozs, pressures rose and vent temps did not progress down---they went up (so pressures are key here.) More, test versions 7 and 8 also followed. Test 7, I disregarded due to bungling it. A version of test 8 now runs in car. Working? Yes. Optimal? No. And so... reason for reload. You might be thinking, "Why bother now with winter coming on?" You're right. But, I'm in "AC mode" at moment so better to get everything done now so come spring... no need to return to unfinished business.



Note: 26 oz liquid injection started with dry hose so weight is not indicative of refrigerant actually in AC system---there is less than 26 ozs when dry hosing it as the final weight read on scale includes refrigerant then in hose.

[wwest]

Karl, there is cotton wadding surrounding the motor shaft bushings, sleeve bearings, good idea is to (RE-)SOAK that wadding with oil while you're inn there.

For best efficiency when you reinstall the blower wheel on the motor shaft you want the edge of the blower wheel as close to the intake opening as possible, not forgetting the motor shaft end play. You could add a extra thrust bearing/washer if the end play seems to high.

[Discseven]

Originally Posted by wwest

Karl, there is cotton wadding surrounding the motor shaft bushings, sleeve bearings, good idea is to (RE-)SOAK that wadding with oil while you're inn there.

Exactly how is that done Will?

[wwest]

Originally Posted by Discseven

Exactly how is that done Will?

With the motor running, bearings up to temp, slowly drip, drop, oil in the area just outside the bearing/bushing, once it stops soaking in you're done.

[wwest]

T-stat may not "calibrate" correctly, wrong placement, colder than factory placement, plus goodly portion of the capillary tube is exposed to cold air when it shouldn't be, wouldn't normally be.

[crownarch]

Originally Posted by wwest

Karl, there is cotton wadding surrounding the motor shaft bushings, sleeve bearings, good idea is to (RE-)SOAK that wadding with oil while you're inn there.

Karl, 3 in 1 makes a electric motor oil specifically for this purpose and it is dirt cheap and works fantastic. Your motor will be whisper quiet if you do this.

[Discseven]

Originally Posted by wwest

With the motor running, bearings up to temp, slowly drip, drop, oil in the area just outside the bearing/bushing, once it stops soaking in you're done.

I did oil bearing some weeks ago but not with it running or up to temp. TY Will. (Was concerned at the time that I might over oil with oil getting into electrical components.)

[Discseven]

Originally Posted by wwest

T-stat may not "calibrate" correctly, wrong placement, colder than factory placement, plus goodly portion of the capillary tube is exposed to cold air when it shouldn't be, wouldn't normally be.

I hear you... but... Fact that t-switch may not be calibrated to spec based on position of probe is not a problem from my perspective. What is sought here is for t-switch to modulate compressor with increasing ON duration the further CW the switch is turned. If it does this to some acceptable degree... I would consider switch functional.

We could extrapolate difference t-switch probe function by considering temp difference in evap from the core (where I have probe) to outside edge near inlet where "stock" probe position is. Am going to guess that temp difference over those few inches is not so great that switch is going to work drastically different. Perhaps I'm wrong. Once 26 oz is reloaded and switch is checked, IF there's cause... probe can be moved.

For added detail here Will, with probe positioned in evap's core, is compressor likely to cut OFF sooner or later as compared to probe near inlet?