A/C dashpot won't raise idle

[FastWoman]

Hi all,

My mostly uncorrupted '78 Z has a factory A/C. The high idle dashpot does actuate when the compressor clicks in, and it will hold a high idle when I let off of the throttle. However, if the engine is idling, and THEN the compressor clicks in, the dashpot is not quite strong enough to increment the idle. I've already disassembled, cleaned, lubed, adjusted, and reassembled the throttle linkages, and they're working very freely. Any thoughts as to how I can solve the problem with the dashpot? It's not a hugely big deal, but I'd still like it to work right.

[ezzzzzzz]

Where in Hampton Roads do you live? I don't own such a new Z myself so I can't answer. You could take a drive over to see Todd at Tidewater Z Auto Service in Poquoson. He could get you straightened out quickly. I'm Mark and the VP of the Tidewater Z Car Club. You're invited to come out to Frankie's Ribs at Fairfield Shopping center (Providence and Kempsville) in the Kempsville area of Virginia Beach next Monday night. Our club meeting (second Monday of every month) starts at 8:00. We gather at 7:00 for dinner and general conversion. You'll meet some great people!

[FastWoman]

Hi Mark,

I live near Yorktown. It's a bit of a hike across the bridge tunnel, but the ribs sound inviting. I might show up! I'm already familiar with Tiedwater Z and do need to connect with them. Part of the reason I was motivated to watch for a Z to buy was my wistful feelings when driving by their location and seeing all the pretty Z's out front. (I had sold my '75 back in the 1990's. My ex made me do it.)

[zcarnut]

Measure the vacuum level at the dashpot and compare it to the intake manifold vacuum level. If there is a large difference then I would suspect the vacuum bottle check valve. It is well known that they can become leaky over time. I’m pretty sure a NOS check valve is NLA, so you will have to use a generic one (if yours is bad).

[FastWoman]

Thanks, Steve! I'll check that tomorrow.

[FastWoman]

... and several days later...

You were right, Steve. I only have about half the vacuum I should. Apparently the leak is not at the vacuum accumulator, but rather in the dashboard switch assembly (i.e. heat, A/C, vent, etc.). That's a job for another day, but at least I've narrowed down the problem. Thanks! :-)