A/C Electrical issues, any diag tips?

[PaulP117]

I ended up needing a new compressor so i figured id just go ahead and commit to converting to r134a since its more readily available to me. I also replaced the receiver dryer and condenser. And now after going through and getting the system vacuumed and oiled and filled i did notice that i have a small leak around one of hoses where i can see the dye leaking out, however i expected the car to at least blow some air for a minute or even at least a few seconds before throwing the b448 code again and killing the compressor. But i made sure the code was cleared, and i could hear the compressor turning on for a few minutes and cycling on and off before the b448 code killed it. But during that small amount of time where the compressor was running for a fact, and the A/C was on Bi Level at the coldest setting and max fan setting i did not feel even a small gust of wind from any of the vents inside the car or the defrost vents. Leading me to believe on top of that small leak, i am having an electrical issue with maybe the blend door not moving? Anyone have tips on what would be the best place to start? 

[Ronnie]

What happens of you put the climate control in ECON mode and turn the fan on high? That way you don't have to deal with the compressor while troubleshooting the fan.

[PaulP117]

Also probably worth mentioning, when my A/C first went out last year and stopped blowing i saw smoke rising from in between the steering column and the steering wheel, but the smoking stopped after turning the car off and back on again and then I had the car checked out anyways at the time fearing for a fire hazard. We saw no burnt or visibly damaged wiring and the smoking stopped so had not much of a choice but to ignore it and keep driving as it was my only vehicle at the time. As far as i know there isnt any wiring thats close enough to the steering column to cause smoke to rise there if it melted apart right? 

[PaulP117]

1 minute ago, Ronnie said:

What happens of you put the climate control in ECON mode and turn the fan on high? That way you don't have to deal with the compressor while troubleshooting the fan.

Had the same effect, no air from any vents when its on ECON and high fan. But something i just noticed, I can feel wind coming through when driving highway speeds on ECON mode with the fan on high.

[Ronnie]

Can you apply 12 volts directly to the fan motor to see if the fan motor will run? 

[PaulP117]

2 hours ago, Ronnie said:

Can you apply 12 volts directly to the fan motor to see if the fan motor will run? 

I just tried this as soon as i got back home thanks to you Ronnie. I fed the blower motor voltage and it kicked right on. I don't see any of the damaged wiring within the engine bay, so now i think it all makes sense. Id think that the blower motors power wire must have shorted and burnt up at whatever length it did inside of the vehicle when i was driving and the smoke just happened to rise at that spot on the column where i spotted it. Im gonna chase down the wiring and check it out. Would you happen to know where the blower motors wiring leads to inside the car? 

[EmTee]

Sounds like a bad blower 'power module'.  That was probably the source of the smoke.  Be glad it failed 'off' - the one in my Allante' failed 'on' and would not turn off without pulling the fuse.

 

https://www.rockauto.com/en/moreinfo.php?pk=85822&cc=1019911&pt=6557&jsn=879&_nck=Ekt6BqBF1pwlXdx0gYlm1esw98pF26vehMm%2FGG3C%2Fl2QOXSJubi7WSpUmUSdg3OxWOs2f5z9h422EONy36O0PjCuaadDqI1r86y%2FvJ1lBqxeBNhI9mMX8H1x0fHFzmF%2BF%2BfJVJLRM%2FPOzb2h9mGwtOklgC7qGdsUwYYJkbMC5HSTqqj9r6dqkkEPp62vDQ%2Bj2YXQZ2rhmyqI4yy2JFS7HjAxNUaXG28SqRjFem%2B5abL0z%2F0kvEl8VVfb%2FV2mi0j%2FzlCxXzuCmvS17fXYcIpvarCnj00pz2JTKuio1EWBauhaZFxHQh6eZ3uxmFfPGMkjU3wlxblrP0Q46Hstu6FNorh7uEve9jMEC2eREHvnIU4jXfY8gLlc0I34ljUEIzeE

 

[PaulP117]

yikes, that sounds like it would be incredibly annoying to deal with ! Ill defintely scoop that module up, it will be extremely nice to have air again for the rest of this summer and the ability to defrost my front windshield again haha. 

[EmTee]

Mine was bad, but the new one didn't fix the blower.  The new module fixed the 'always on' problem, but I had to replace the BCM to make the blower function properly.  Follow the troubleshooting flowchart in the shop manual.

[PaulP117]

also i was just curious if anyone knows the correct math for the pag oil and refrigerant capacity on the 91 Reatta for r134a. R12 says 2.38 lbs of r12 which would equate to i think like 1.9 lbs of r134a? and the r134a pag oil should just be 8 ounces i think? 

[minor4326]

My search tells me two ratios: .75 ratio and a. 65 ratio of R12 to R134a. I also read " It is recommended that you keep the R12 unit’s charge at 75-85 percent for the conversion." 

[EmTee]

Since my Allante' was converted to R134a before I bought it and I didn't know how much to add, I followed the instructions for the "Insufficient Cooling 'Quick Check' Procedure" in the shop manual.  The instructions are to check by hand the temperature difference between the evaporator inlet tube and the accumulator.  "Proper operation with an adequate refrigerant charge is indicated if both the evaporator inlet and accumulator feel cooler than the outside air and both seem to be the same temperature."  This seems to be working for me, as temp at the center vent is about 45° F with air temperature about 80° F.  (If I recall correctly, low side was running at 55 psi and high side was 275 psi.)

[Ronnie]

3 hours ago, minor4326 said:

My search tells me two ratios: .75 ratio and a. 65 ratio of R12 to R134a.

That sounds like you are talking about mixing R12 and R134a. That is a no no. They are not compatible.

[PaulP117]

I do wonder if I've overcharged the system with bad math, My High Side service valve is pushing some air out after i charged it using a GM r134a machine at 1.9lbs of r134a and 8 oz of PAG oil. Either that or could just be a bad valve core.

[Karlw144]

Can’t remember for sure, but did the compressor come with a charge of oil? At one time you had to count that as part of your oil charge. You might have too  much oil in the system. I’ll try to do more research. 
karl 

[EmTee]

7 hours ago, PaulP117 said:

Either that or could just be a bad valve core.

Yes, the service manual says to be sure to cap the low side port because the Schrader valve will leak.  I confirmed that the high side port on my Allante' does leak, so I have both ports tightly capped.  So far, so good...

[dship]

FYI, Rock Auto has low side and high side A/C retro kits for sale. I looked for my '91 Reatta, but they are for sale all years Reatta.  Go to 1991 BUICK REATTA 3.8L V6 A/C System Service Valve / Core / Cap | RockAuto. 

[EmTee]

I think it was the GPD assortment that I bought.

 

https://www.rockauto.com/en/moreinfo.php?pk=5916000&cc=1019922&pt=6992&jsn=12&_nck=Ekt6BqBF1pwlXdx0gYlm1Vbc6OkIAOtIax55q04f8E%2FhJSYt6qLNc21gKdyXP8KWQBlyLi3Me4J6bex8cuQwOnprvHyJD6K2JGGGdqWgClMguoL5OHfvHm%2FXxe9%2BboF2ERZn5izwl4qpdvSKGX%2FqF3hqmx5f21IXUfuy9X%2BQS%2BUrQIM5WF0sBoOIcmdhZYuQmRLEse%2FqxC%2FSJbSuXRJzLpLxbFE77vvaRA73dKb%2BsOvH2zkeBrL9AelbtR2QxpwzsQs1pY6qnIJZgRuY1nCFuIvse79H1keyvfHTkxS796G%2B0nCvg0Ix%2BHjVmKdQlsKavjZbYXpdAq984O2SccfHPz2Iwm7tsutFVNyVXPxvT1F3oTIsSNqp2O35XQTSdDprvaN%2Fxjtdekq6Th4NmBfiWgxnKB8XO27ABXo5xSfcoZ8uLd%2FrRtBwgrKd2QRq5gyTRvMWq%2FXfyR7lvRDD%2Fq0PmwChOj3omnJNBCRunIblRwOnJmvTcWo4lewHl%2FBRfTFHdJEcrXKVyIf7Sl4lKZBOhQ%3D%3D&jsn=12&_nck=Ekt6BqBF1pwlXdx0gYlm1Vbc6OkIAOtIax55q04f8E%2FhJSYt6qLNc21gKdyXP8KWQBlyLi3Me4J6bex8cuQwOnprvHyJD6K2JGGGdqWgClMguoL5OHfvHm%2FXxe9%2BboF2ERZn5izwl4qpdvSKGX%2FqF3hqmx5f21IXUfuy9X%2BQS%2BUrQIM5WF0sBoOIcmdhZYuQmRLEse%2FqxC%2FSJbSuXRJzLpLxbFE77vvaRA73dKb%2BsOvH2zkeBrL9AelbtR2QxpwzsQs1pY6qnIJZgRuY1nCFuIvse79H1keyvfHTkxS796G%2B0nCvg0Ix%2BHjVmKdQlsKavjZbYXpdAq984O2SccfHPz2Iwm7tsutFVNyVXPxvT1F3oTIsSNqp2O35XQTSdDprvaN%2Fxjtdekq6Th4NmBfiWgxnKB8XO27ABXo5xSfcoZ8uLd%2FrRtBwgrKd2QRq5gyTRvMWq%2FXfyR7lvRDD%2Fq0PmwChOj3omnJNBCRunIblRwOnJmvTcWo4lewHl%2FBRfTFHdJEcrXKVyIf7Sl4lKZBOhQ%3D%3D

 

The Allante' has an odd high side port that requires a special tool to adapt to a standard R-12 port.  Whoever converted the system to R-134a installed a typical QD adapter fitting which doesn't allow for opening the OE valve when my gauge is attached, so I removed the 134 QD adapter use the "J-XXX" tool to attach to the high side.  Anyway, that means I use the R-12 cap from the kit above to secure the port.  So far both caps seem to be holding.  If necessary, the next step would be to evacuate the system and replace the valves in both ports.

[PaulP117]

Went ahead and bought the blower control module and upon taking one of the connectors off I think I definitely found the exact cause of my smoke haha

[EmTee]

Use an Ohm meter to check the power module for continuity (i.e., a short-circuit) between pins C2-B (where the burned wire attaches) and C2-A (the 4-pin connector).  Those two pins should be isolated unless the power module transistor has shorted internally.  The power connection (C2-B) must have been dirty or loose to cause that damage.  As seen in the schematic below, up to 30 Amps can flow through that connection before the fuse would blow...

 

[2seater]

On a Reatta, at least for 1990, the blower module receives power from a fusible link, hot at all times. What the power capacity is, is unknown, but it is the source of the continuous fan even with the key off.

[EmTee]

Yes, I question the "HOT IN RUN" note on the Allante' schematic.  While technically true, is is actually 'hot' any time the battery is connected!  Mine had a shorted power module when I bought it and the PO had pulled the 30A maxi-fuse in order to shut it off.

[2seater]

I mentioned it in case there was a repair in the plans that would replace that plug. It will be hot as long as the battery is connected. Always good practice to disconnect the battery ground when doing electrical work.