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Update--70 A/C blower. Working thru Cadillac Tim's book

Started by Jeff Rosansky CLC #28373, June 18, 2016, 05:36:02 PM

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Jeff Rosansky CLC #28373

I've read a lot of posts on climate controls, but now I have one of my own to post.

70 Deville.  I am trying to get the blower working properly.  I am almost positive the transducer is bad but that is a separate issue. 
I am trying to manually put the blower on hi (Auto HI) and it only stays in low.  Same with ICE position. 
I have gone down the steps in Cadillac Tim's book and it appears the resistor board in the power servo is bad.  Here is what I have found:
POWER SERVO--yellow has power.  Tan has no power.  Brown/white has reduced power (using a test light and it is dimmer than full power such as the yellow wire).
RELAY--Orange has power. The stand alone wire has power. the White/Brown wire has the same dim test light and the dual ground is good (reversed the testlight and it is a good ground).

According to Tim's book, if the Tan wire at the servo has no power and the brown/white wire does then the resistor board is bad. My question is: what constitutes power?  A dim test light shows power, but not full power.  Is just having power enough?
If the resistor board is bad, has anyone tried a field repair or does it need replacing/repair by someone like Cadillac Tim?

Thanks,
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Smelvis

Hmm that's interesting. I'm not sure the answer but I can poke around next time I'm in the garage and take some readings.

Have you properly tested the relay? I recall when I was working through the hvac I was about to replace the relay as it clicked but still wasn't getting the hi blower speed. Before I did I jumped full battery power to it and it freed up. Apparently it was stuck and not making full contact. Then I had full blower power.

Jeff Rosansky CLC #28373

I did replace the relay a year or so ago, but that doesn't mean much of course. It does 'click.'.
To jump the relay, which terminal did you put the full 12volts to?
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Scot Minesinger

When Tim writes about having power, fairly certain he means the full 12 volts.

Have you verified that ground on blower is good?  A lot of times it goes bad because the compression force that keeps it tight is an old gasket.  Clean, tighten, and check to be sure - that is an easy one.  If ground is good have you verified that fan operates at full on battery voltage?  When you do this for some reason I had to have my climate control on??
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Jeff Rosansky CLC #28373

The dual ground wire is good. I do get a 'click' from the relay. Are you talking about supplying a full 12 to the brown/white wire that is less than 12?
Now that I think of it, I am not sure if the brown/white wire is getting power from the servo to the relay or relay to the servo........ will need to check that.
If it is the servo rhat is bad, has anyone done a field repair on one?
By the way, happy Father's day to all.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

cadillactim

Jeff

By "power" I mean battery voltage (12-14 volts).

You can field test the resistor board this way:

1. Looking at the front of the servo, connect an ohm meter to te left and center terminals (wire connector unplugged).

2. With arm all the way out (full a/c), reading should be 0.00 to 0.02 ohms. As you slowly apply vacuum with hand vacuum pump, resistance should increase to approximately 0.06 ohms, 0.10 ohms, and at halfway point 0.15 ohms. The as the arm moves the rest of the way in to full heat, readings should reduce in same order, reading 0.00 to 0.02 ohms at full heat.

3. Sometimes readings are lower in middle (0.10 ohms halfway), which is acceptable. Any reading above 0.03 ohms at full ac/heat or above 0.17 ohms halfway are too high and resistor board needs repaired or replaced.

Tim

Tim Groves

"Cadillac Kid" Greg Surfas 15364

Tim/Jeff,
I took this NOS '70 Power servo and tested it between 0  through 10 inches of vacuum.  The numbers I got were different than yours (calibration/decimal place?), but of course they go in assending through descending magnitude as the voltage is reduced and then increased as the fan goes from high through low back to high.
Your issue if I remember correctly is the lack of a higher speed.  I might suggest unplugging the blower relay connection, checking to verify you have 12 volts at the orange terminal and manuually jumping the orange and the tan wires.  If that gets you high speed I would suggest the blower relay is bad.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Jeff Rosansky CLC #28373

Thanks

Will probably be a few days before I can get to it but I will check

Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Smelvis

I didn't take any readings today....figured you got Tim the guru on it, you'll be in good shape.

Jeff Rosansky CLC #28373

Thanks. Will not get to it until the weekend.
Jeff
Glad your trans is ok.
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

cadillactim

Jeff

I noticed I got the decimal points in the wrong place. Should be close to following:

0-.2 ohms (full a/c arm all the way out)
.6 ohms, 1.0 ohms
1.2-1.5 ohms
.6-1.0 ohms
0-.2 ohms (full heat, arm all the way in)

Resistance readings need to vary between 0 ohm to 1.5 ohms. There can be some slight variations, but anything higher than 1.7 ohms at middle position is too much and will slow the blower down too much.
Tim Groves

Jeff Rosansky CLC #28373

Looks like the resistance is too hi. Got 1.5 ohms on full ac mode with a cheapie Harbor Freight tester set on the lowest scale of 200. No change aa I move the arm thru its travel. I cleaned the contacts inside with no change.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

chrisntam

Courtesy bump for my ol' pal Jeff.

So the servo is bad?
1970 Deville Convertible 
Dallas, Texas

Jeff Rosansky CLC #28373

Yah, looks like it. Tim gave me a few tips that I will try........ if I have the energy. Another hot one here today. Got to 105 in the garage yesterday. Makes me just want to sit inside on the couch.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Jeff Rosansky CLC #28373

#14
Well, well, well. Turns out Uncle Jeff was chasing the wrong rabbit down that hole.
I cleaned up the wipes and contacts in the servo-but still had the same problem.
So, I got out my trusty wiring diagram and got to looking. Turns out the white/brown wire was only getting partial power because it was backfeeding thru ths servo.  You see, I took the readings with the connector still connected to the servo. The brown/white wire at the servo is directly the same wire at the relay.
So, with the key on which gave me low blower, I took the connector off the RELAY  and put 12 volts to the brown/white wire at the relay connection. This put 12 volts to the brown/white wire at the servo but still allowed me to have the connection at the servo.
Well Uncle Jeff had full hi blower! I had been chasing the servo when my problem was at the relay.
I had not thought it was the relay because I could hear it click. I assumed it was working correctly.
More to follow.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Lucas Feininger #15674

I think Uncle Jeff deserves a nice frosty glass with an ice-cold malt beverage in it. Excellent work and thank you for sharing your discovery with the Forum.
Lucas Feininger
1965 Sedan de Ville
1965 Eldorado
2014 SRX
CLC #15674

"The only way to travel is Cadillac style"

chrisntam

Isn't it a great feeling when you fix something like this?!?!?!

8)

I remember long ago, my small block chevy was not running right, like it was running on 7 cylinders.  Did a bunch of stuff that didn't fix it.  Finally pulled the valve cover, backed off the rocker arm nut a bit and it smoothed right out.  I thought, I can fix anything!

8)
1970 Deville Convertible 
Dallas, Texas

"Cadillac Kid" Greg Surfas 15364

Jeff,
I'm glad you were able to chase down the problem without throwing a dozen parts after it.  The diligence and effort has paid off.  Those relays and their connections are a major culprit on the 60s and 70s ATC systems.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Scot Minesinger

True, my hi fan stopped working on 1970 DVC a couple years ago and made a post about it.  Just took cleaning of connections to fan relay, one of the least expensive repairs.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty