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96 Park Avenue Ultra

Hi, I drive a 1996 Buick Park Avenue Ultra and my front dash blowers do not blow air (hot or cold). The defroster and the floor vents work fine, but not the front vents. I have heard this means something is wrong which has put my HVAC system in “default mode.” Could this be a disconnected vaccum line somewhere and if so, where do I look for it? How do I troubleshoot this? I should also add that the electronic controls and display all seem fine.

Everything is either under or behind the dash. It is unlikely that a hose simply came off. More likely would be a vacume motor has gone south, or most likely a bad HVAC control module. Without the factory manual and the trouble shooting charts, plus the diagnostic equipment, it is all guess work and replacing parts. One thing you can check is to make sure that you have vacume going to the controler (should be around the right passenger kick space with colored vacume lines going to it). On my Buick I had a vacume line in the engine flop down and got a hole burned in the line, causing no vacume to the HVAC controler. I found it by running a long hose from the engine to the controler and then back tracked to find the problem. It had similar symptoms with no air coming out the vents.

The most likely culprit is going to be a rotten vacuum hose under the hood. Find the vac line where it goes through the firewall and check for vacuum with the engine running. There should be at least 15 inches of vacuum. If not, trace vac line to the storage ball. I can’t remember where it’s at, but follow the vac lines and I bet you find it.

I pulled the cover under the passenger side dash, but I couldn’t find any vacuum line, just a bunch of wires and some fuses/ relays that I didn’t know where there. I found one shiny black line about 3/8" in diameter that runs all the way around the front hood from the passenger side firewall, under the radiator and back through the driver side firewall. It says “NOT REPAIRABLE” on the line and it looks like it has been taped up in one spot. Could this be a vacuum line? What size is the vacuum line I am looking for? How do I check for vacuum on the line? Where might I find my HVAC control module?

Thanks for the quick responses!

OK, so I was just looking around under the hood, and I found some vacuum connectors that were just falling part. One was at the top of the engine near the rear under the engine cover, and the other was between the engine and the air filter. The two lines seem to connect into some system (forgive my lay man terminology). I went to the auto parts store, bought some connectors and now the air comes through the vents! It isn’t very cold though and seems to blow much better through the driver side than the passenger side. I do have dual climate controls, so maybe I have a few more kinks to work out. My question now is, since the air blows and seems to get cold(er) do you think it just needs a good charge? I have to admit, I’m a little scared of digging too deep, how much does it cost to have a mechanic charge it?

My question now is, since the air blows and seems to get cold(er) do you think it just needs a good charge?

Well a good charge means the right charge, not too much or not too little. Too much is as bad as too little.

My recommendation is to find a local A/C shop that someone local (neighbor friend, relative etc.) has recommended. Have them check it out.

Note: up north many A/C shops hide out as radiator shops half the year.

An AC recharge and leak check will run anywhere from $100 to $200 generally. At that age it probably is a little low on charge but don’t be surprised if they find hose leaks or other issues that they’ll want to do first that can be quite expensive.

Thanks for the comments!

So, I went found where all of my vacuum wiring routes to and replaced all of the connections (which were just shot) and now the air seems to be even better! Wow, at least the logic is there! I did some reading on how to charge an AC system and I just decided to go for it, long story short, I now have air conditioning and I hardly spent a dime. One thing, it seems to take a little bit for the air to come through the front vents, but once it gets going, it is wonderful. Thanks for all the help!