AC burden on Engine

[GDI]

I have AC in my '74 2002tii that was put in just prior to my buying last year, and works pretty well considering.  It is a Behr unit and has an modern (Sanden?) compressor.  My problem is that it really seems to drag on the engine, when I come to a stop light the engine will sometimes die, and on accelerating from lower RPMs it will miss a lot  - I have to get the RPMs up to keep power.  The car generally runs very strong with the AC off, occasionally I have some missing/rough running when lugging the engine.  

 

Any ideas of how I might diagnose/fix the problem?  I am tempted to bump the idle up, but I think that will just cover up the root cause.

 

Thanks

[Glen Karr]

GDI,

I have the same AC in my 74 Tii.  I have the idle adjusted up to about 1000 RPM.  This seems to be about right and I haven't had a problem with stalling.  There shouldn't be much drag with the Sanden, at least not as much as with the original compressor that was installed in 74.

Glen

[TobyB]

2 thoughts-

 

first is timing.  See if something unusual happens (a lot of retard, probably) when the engine slows

below 700 rpm.  That often happens with a worn distributor.

 

Second is an air leak.  Worn throttle shaft, especially, or loose macaroni, or broken gaskets.  That sort of thing.

A smoke test is actually pretty useful on a tii.

 

t

[Vicleonardo1]

3 minutes ago, TobyB said:

 

Second is an air leak.  Worn throttle shaft, especially, or loose macaroni, or broken gaskets.  That sort of thing.

A smoke test is actually pretty useful on a tii.

 

t

Or just about any car.....

Oregon smoke test: 

[GDI]

Thanks - I'm familiar with the "Oregon" smoke test - I utilized in my old '02 that I drive in college,  but I need to Google Toby's version.

 

I need to check the timing and inspect the distributor.  Good excuse to upgrade to a modern timing light and I may put in one of those fancy electronic ignitions with blue tooth and ApplePay...