MACS Monthly Newsletter - 2020 - FEB4

February 2020

techinfo.toyota.com

shaft will not. This way all the other accessories driven
off the belt will continue to operate.
The assembly includes rubber segments to absorb
shock in the operation of the compressor, but if the compressor binds, the reverse torque will cause the limiter's
plastic hub spokes to crack, resulting in the separation
of the pulley from the pump shaft plate. See Figures 5,
6. And by probing the narrow space between pulley and
plate, the technician confirms that is the cause of the compressor failure. Now the question: what to do?
The by-the-book repair is to replace the compressor of
course, but the technician decided to try a jury-rig repair,
"just to see if it would work." The approach was to drill a
hole through the plate into the pulley and thread in bolts
to hold the parts together, so the spinning pulley would
drive the plate and the compressor shaft to which it was
attached. He did exactly that, turned on the A/C and no
real surprise, the compressor operated, apparently normally.
Does it seem this "fix" has no downside? It takes perhaps 15-20 minutes starting with the car on a lift, so a
job ticket of up to $100 would seem to be something that
would delight a customer with a 12-year old car and the
shop would make a profit.
Not so fast! Yes, the compressor ran and did cool the
cabin in the YouTube test, but let's look deeper. What
causes that damper limiter to fracture? Answer: binding in the compressor's moving parts-a seizure of some
sort. In this case the technician found that the compressor
could be turned with the engine off and then ran when he
started the A/C.
So, would putting a little oil in the compressor be
enough to keep it running? Almost surely the answer is
no. The seizure may be intermittent, but if it happened
once, it's surely going to happen again and there's almost
assuredly no way it can be durably "fixed."
Sure, the car is far from new, and might have about
100,000 to 125,000 miles or so on the odometer. The book
repair is to install a new OE replacement compressor,
but that's not going to be cheap. However, if you (or the
motorist) looks on line, he might say, "Hey, I saw a replacement compressor for my Corolla for only $150, so
maybe that might be available through normal aftermarket sourcing for perhaps $350 as a reman. But for either
price you'd have no way to verify the internet listing really is a duplicate for the OE pump until you get it and
try to install and connect it. In fact, we'd almost be ready
to bet against it. One tipoff is that typically there are visual physical differences with some of these low-cost
compressors allegedly for the 2009 Corolla. So, there's no
assurance the one you might buy on-line (or even some
aftermarket sources) will match the original, including a
break-away pulley. It might not even come with a clutch.
Further, you'd have no guarantee that even if the compressor does seem to be the one for the car, you don't
know if it's really new, maybe a reman, or just a cleanedup used compressor in a nice-looking box.

Figure 6: Stepped illustration shows how pulley and belt
continue to operate even if compressor seizes and pulley
separates from compressor shaft.
The Denso compressors that we've seen on line that
are more likely to be replacements for what's on the car
were in the range of $600 or so. Here again, is it a new
pump and does it come with a factory warranty, which
normally would be priced at around $1000.
That new unit price makes it awfully tempting to try
the YouTube repair. You might think of telling the customer, "What have you got to lose?"
Here's what: when that limiter breaks, there's a fairly
good chance that the compressor has not disintegrated
internally. So, it wouldn't be unreasonable to think that
a replacement compressor would be all that's necessary.
Whereas if you do the jury-rig repair and the compressor
runs for a short while and then fails, it's more likely that
there's compressor debris spread throughout the system.
Which would require replacement of both the condenser
(not cheap because it has an integral receiver-dryer) and
expansion valve at least, maybe hoses, and possibly even
the evaporator.
So, after looking at all these facts, what's the best decision in a case like this? Our thoughts: if you can get a lowmileage compressor from a wrecking yard, that would be
our preference. But talk to the customer to consider the
options, because if the chosen repair, whatever it is, fails
in just a few months, it has to be a failure the customer
will accept. He surely won't be happy with it, but he can't
blame you for failing to lay out the choices honestly.
A 2009 Corolla is, by today's standards, certainly not
an old clunker. The average age of cars on the road is just
over 11 years, so it's entirely possible an owner will be
keeping a car like this for a number of years. And if it's
been well-maintained and in good shape, a durable A/C
repair for an investment of up to $1000 or even somewhat
more, is not something limited to luxury cars. n

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MACS Monthly Newsletter - 2020

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