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1988 Cadillac AC Computer?


I have a 1988 Cadillac Fleetwood that is in great condition! It runs like a dream and just a few weeks ago topped 100,000 miles.

I have one problem, though. The AC doesn’t work. I took it to a mechanic and he told me the computer climate control only works with old freon. I would need to have it updated somehow but he wasn’t sure how. So, basically, I have a perfectly functioning air conditioner that can’t recognize whatever the new version of freon is.

Does anyone know a fix for this? I would rather not spend tons of money on this car - it’s great and all but a 1988 Caddy will only last me a few more years anyway.

Vehicles made before 1993 require R12 unless retrofitted to R134a. I believe the mechanic is mistaken about the climate control system because it has no way of determining what the compressor is charged with. Your AC has probably lost it’s Freon charge and that’s why the it does not work. Take your Caddy to an independent AC shop and have it checked out. I would have it converted to R134a but that decision will be up to you.

+1 to missileman’s post.

The problem with conversion is that the system would need to be cleaned out, any eaks fixed, and recharged. Shops used to say that new components were necessary because the R134 was thought to require higher pressures to do the job of effectively disspating the heat (it isn’t as efficient), but I think the general consensus among the AC guys now is that the R134 works fine, just not quite as well as the old R12.

Anyway, most radiator shops around here specialize in AC too. You might not find one that has any R12 left anymore (its manufacture was banned some years back), but they’ll be able to advise you. And hey, if the quote is too high, just say “no”!

That makes no sense at all. The HVAC board has no way of knowing what the charge is in the air conditioning system unless it is low on freon. What is the problem with the system? Low on freon, a leak, or the air conditioning controls itself?

I think missileman already said it; the system has probably leaked out the freon.
In my mind, low on freon = leak. And leak = low on freon.

My commenst were based on the fact that the R134 doesn;t dissipate heat as well as the R12. Shops used to think when the manufacture of R12 was originally banned years agothat the compressor needed to be changed and the system operate on a higher pressure, but everyone agrees now that that is not the case.

Hey, maybe this will help. It’s the sheet given to us by the mechanic at the shop. It’s entirely possible I’m describing the issue wrong.

I would call a large, independent AC shop. I owned a Cadillac years ago that needed the AC recharged. After the recharge…the AC and climate control would not work until the negative battery cable was removed for a minute or so. Checking with a professional AC shop should get you the right answer and procedure for getting you back on track. My Caddy had a tag near the battery with a note for charging the AC system. It had to be reset or it simply would not work.

Translation: Please take this 25 year old relic someplace else…

Step one. Convert to and recharge with R-134a refrigerant. Step two. Find leaks. Step three. Repair leaks. Step four. Recharge system. Step five. Hope and pray the “climate control system” functions normally. If you can reach Step Five without spending more than $1000 you will have done well…Good Luck…

That copy of the repair order is pretty vague as to specifics and trying to sort things out.
Going by the RO, it’s stated that the system pressures are normal and I assume (right or wrong) this means the compressor is engaged and both high and low sides are where they need to be.

If that is the case then maybe there’s a blend door issue? Some ifs here, but IF the compressor is engaged and IF the engine is allowed to idle for a while with the A/C on the accumulator pipe should be getting cold and sweating along with a condensation drip underneath. If so, the blend door is a possibility anyway.

I’m not a Cadillac expert (nor do I want to be) so the above is general in nature only.

That printout doesn’t appear to be OP’s actual repair order.

I believe it’s only an Identifix hit. In other words, somebody logged onto Identifix and did a symptom search and came up with that.

Thank you for clearing that up db. I’m not familiar with Identifix but if that shop is relying on a fee-based website to come up with a diagnosis then one has to wonder…

Might be time to find another shop. :slight_smile:

I’ve never used Identifix, so I don’t have an opinion as to its effectiveness.

Personally, I prefer old fashioned diagnosis, factory service manuals and factory TSBs

I’m in agreement with you on that.