Trouble Shooting - under dash chatter noise

[bymec]

I replaced the compressor on my 2009 Impala last week.
Vacuumed the system, added 2oz PAG oil to the compressor and another 1oz to the line.
Recharged the system with R12-A using the conversion factor given to replace R-134A.
Worked nicely for a week but now no cooling. Getting a loud chattering noise under the dash when the A/C is turned on.
Getting 46psi static pressure on both high and low sides. With A/C compressor on getting 30psi low side and 65psi high side (75 F outside).
Any suggestions?

[Tom Greenleaf]

Welcome:

Can't speak for much on behaviors of R-12a I think sold as "Freeze 12" also.

So a question for now till another comes along is WHY would you use an alternative when this total system was well designed for 134a?
(edit in) I ask because IDK if this refrigerant is the cause or another more common something like an actuator for ducts. Do they work and direct air where you request?

T

[GM Tech]

W-cars are know for stripped actuators- they will "chatter" for 2 minutes or so- trying to position the blend doors-- so is this what is going on? You can buy new ones at Autozone or rock auto or ebay-- heck you can take the actuator apart and buy a new steel gear to replace the plastic stripped out one....

[bymec]

Thanks for your replies Tom and GM Tech. Sounds like my problem is the blend door actuator. Hope the problem was not caused by my switching to R-12A. To answer your question Tom, I switched from R-134A to R- 12A because that is the only refrigerant that seems to be sold in this part of the country. Both are non-ozone depleting but the R-12A also claims to be less harsh on the environment.
D

[Tom Greenleaf]

Seems like you've found it and know the fix. Thanks for posting your findings,

Tom

[Cusser]

For actuator replacement on my 2005 GMC Yukon, I had to grind a 1/4-inch drive 5.5mm socket shorter at both ends to get it to fit one of the two mounting screws: the hump was in the way !!!

I used a Dorman aftermarket replacement, cross-referenced to the GM number on the malfunctioning part. After install, had to reconnect battery, wait 10 minutes. Then turn on ignition, wait 10 minutes. I read that instruction on-line.

[Tom Greenleaf]

Love it! I've "ground down" assorted sockets and tools for one use or from some cheap old sets.

BTW - check but TMK 5.5mm is also exactly 7/32nds in SAE! You never think that size anymore once more common,

Tom

[Cusser]

Love it! I've "ground down" assorted sockets and tools for one use or from some cheap old sets. BTW - check but TMK 5.5mm is also exactly 7/32nds in SAE! You never think that size anymore once more common. Tom

Yeah, I also had a 7/32nds socket in one of my socket assortments (found that out that day). This was first time I've ever had need for either size (not positive, maybe I ground-down the 7/32nds socket !!!). Still don't know why so many times a weird size is used; in this instance an open-end or box wrench would not fit either, the head was recessed. A longer screw with a shoulder so the head extended for access would be cheap to have engineered in, but maybe service dollars lost was taken into consideration.

On my daughter's '98 Pathfinder (and on on my '98 and 2004 Frontiers, I believe) the front brake bleed screws need 10mm wrench, the rears take 8mm !!! So come on now, and not only a GM issue !!!

[Tom Greenleaf]

Sorry to original poster on carrying on with this but it's part of the game for me - still. Knowing what sizes are the same or close for SAE and Metric and which ones you can wreck having tons of each (I do) and easier to bend, grind or alter a tool than wait or go hunting for something.

BTW your 8mm is also 5/16th but for bleeder screws or lines can end up no swing room for a wrench and can't just cut and use a socket for things - figure it out with what you have.

With just a propane torch can bend a wrench for some things probably available as a set of "obstruction" wrenches and use a couple quite a bit still and not working on stuff that much anymore.

BTW again just of interest tech schools of ages ago had lots of Ford teachers so gravitated to the brand when it was unique a bit.

Grease fittings came with plugs not fittings that take an 11/64th socket or wrench to remove and put in a real grease fitting. No other size works. Most never get grease fittings from new if hard to get to, I do and that joint never wears out if tended to on schedule.

I'll never figure out why even some nice sets of Metric do not include 16mm or 18mm both of which nothing really works for so need to buy two more to complete the sets that costs as much to complete as all the rest did together!

Tom

[GM Tech]

W-car actuators are a piece of cake-- no grinding, no problem...just tight- but they all are....