A/C cutting out under vacuum:ACR, normal?

[toddt]

Here's something I've been wanting to ask about:

Is it normal, under medium acceleration (or mild acceleration up a hill--i.e., high vacuum situations) for the air conditioner to start blowing hot air?

For a long time, I thought there was simply a vacuum switch to cut the compressor out when engine demend was high, to prevent the A/C from degrading the performance of the car.

I even complained about it when I took it in for warranty repairs. (Dublin Dodge, CA)

The service writer told me "They all do that." (of course)

But I kept getting more and more skeptical.

I could believe a cutout under WOT, but HOT? (half open throttle, hee hee)

More and more, the phrase "BS" rang out in my brain.

So--What is the answer Vipites? Does ACR stand for A/C, Restricted?

 

[ACR Larry]

Your service writer is correct. They all do that. No pump, more power.

 

[JonB]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by toddt:
Is it normal, under medium acceleration (or mild acceleration up a hill--i.e., high vacuum situations) for the air conditioner to start blowing hot air? The service writer told me "They all do that." (of course) <HR></BLOCKQUOTE>

Actually, ACRs are more likley to do it than Non-ACRS !

100% Normal

 

[Jim Sullivan]

Hi Todd,
I had the same problem here in Florida and added a vacuum reservior in line per LucNoel on our web page. Not a problem anymore. Check the archives.

 

[Serious Eric]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by toddt:

Is it normal, under medium acceleration (or mild acceleration up a hill--i.e., high vacuum situations) for the air conditioner to start blowing hot air?
<HR></BLOCKQUOTE>


Not to nitpick, but I think what you actually mean is that under LOW vacuum conditions, i.e, higher intake manifold pressure experienced during acceleration, the A/C blows warm. Max vacuum (min intake pressure) is achieved at high rpm with a closed throttle position ... like coasting downhill. Min vacuum occurs at low rpms with WOT.

Had an old truck with vacuum driven windshield wipers. Going uphill in the rain was a ***** ... the wipers would just stop. Downhill they'd flap like some insane bird.

BTW, my GTS' A/C behaves same as you describe. Worse on my '99 that had headers, smoothies, K&Ns and an opened up airbox. I believe that the better the motor breathes, the worse you'll experience this problem.

 

[Gerald]

I would attend to agree 100% with Todd.
Everyone has turned off their A/C in other cars as well as their vipers and switched it to the Vent position where it just brings in air from the outside. When that is done manually, the parts that cool the air (don't know what it's called, condensor, evaporator, etc??) are still cold and you will experience cold air (as cold as normal A/C) for approx another 30 seconds..

If that is the case, then why does HOT air blow out all of a sudden under heavy load? You think the engineers would have the A/C shut off and bring in outside air that is still somewhat cooled by the cold A/C parts, vents, tubes, etc and would'nt even notice the compressor shutting down.... And why would it be bringing in HOT engine air that quickly?


Gerald

 

[Greg 99ACR Red and Silver]

It may be 100% normal, but who likes hot air blowing at them on a hot day? My AC would blow hot air when accelerating up hills in 6th gear.

I took mine to the dealer and they installed a check valve in the AC vac line (under warranty). The problem went away. Insist on a fix. It's worth it.

 

[ACR Joe]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Greg 99ACR Red and Silver:
..... installed a check valve in the AC vac line ..... <HR></BLOCKQUOTE>

Can you post photos, part number and relevant details?

 

[Greg 99ACR Red and Silver]

ACR Joe:
I don't have the details. Dave Jenkins here in Socal repaired it for me.

I was surprised to see that this fix is not so well known.

Perhaps Dave can elaborate here. He contributes to this board.

 

[toddt]

Thanks guys--

It's good to know that my tech was right! If it's an idiosyncracy of the ACR I will NOT fix it, in the name of keeping it bone stock. I want to present and drive the car with all its warts and glory...a monument to the summit of the 20th century sports cars! 1999 Dodge Viper ACR. The greatest of them all!
=)