Bypass A/C compressor on 3.1 litre

[hforcier]

Hey there all and greetings from Quebec, Canada ...

I am trying to locate instructions, and a diagram, to bypass the A/C compressor on a 1994 Pontiac Transport with a 3.1 litre engine. I am not sure what controls what in terms of the pulleys, and dealerships are less than helpful. There are no belt diagrams under the hood, no instruction manuals either.

I did this with a 1995 Beretta and gained 30% in gas savings as well as the full extent of the engine horse power capability that I did not have before. It was a pretty extreme result, but I don't expect as much from this ... I just want to give the engine a chance to survive a little longer, and I can use any edge I can get to do that. You know how it is ... Gotta see those girls through colledge!

Anyway, thanks in advance for all the help and replies and help. Diagrams, instructions, a Jpeg of the hood diagram ... would all be welcome.

Best regards.

Henri

[cdru]

Presuming that the AC clutch isn't stuck engaged, you won't see any performance increase. It basically acts as an idler pully freely spinning. If you take your belt off and can easily spin the compressor pully, it's not stuck.

But to bypass it, often you can just get a shorter belt and not put the compressor "in the loop". This leave the compressor still there while there is no chance that it can drag down the system. You'd have to look and see specifically on your van if this is a possiblity or if something would get in the way of the belt path.

[hforcier]

Originally Posted by cdru

Presuming that the AC clutch isn't stuck engaged, you won't see any performance increase. It basically acts as an idler pully freely spinning. If you take your belt off and can easily spin the compressor pully, it's not stuck.

But to bypass it, often you can just get a shorter belt and not put the compressor "in the loop". This leave the compressor still there while there is no chance that it can drag down the system. You'd have to look and see specifically on your van if this is a possiblity or if something would get in the way of the belt path.

The good news is ... I found that there is a part availlable through Canadian Tire. There is a listing for a 3.1 litre belt with no A/C . The problem is that there is a tensionner that acts on the belt itself and a number of pulleys that I am not sure of. Without a diagram that is usually under the hood, I can't identify these and I don't want to make a mistake ... It runs very well, so far.

Thanks again for that reply.

[LMP]

as cdru says, when the a/c is off and the pulley just free wheels, there is no power penalty. However, what a lot of people ignore is that a/c is on not only when you press the A/C button: it is automatically turned ON whenever you choose DEF of FLOOR/DEF positions. THis help defog faster cause A/C deshumidifies the air in addition to the heat control you apply . SO a lot of people run on A/C when they think they do not, and pay the fuel bill for it. ALso A/C is automatically disabled once temperatures go around 0°C and below, but engine heat al low speed in city driving can raise refrigerant pressure enough to turn it on anyway.

[hforcier]

Originally Posted by LMP

as cdru says, when the a/c is off and the pulley just free wheels, there is no power penalty. However, what a lot of people ignore is that a/c is on not only when you press the A/C button: it is automatically turned ON whenever you choose DEF of FLOOR/DEF positions. THis help defog faster cause A/C deshumidifies the air in addition to the heat control you apply . SO a lot of people run on A/C when they think they do not, and pay the fuel bill for it. ALso A/C is automatically disabled once temperatures go around 0°C and below, but engine heat al low speed in city driving can raise refrigerant pressure enough to turn it on anyway.

Yes, and that is why I want to bypass this system so baddly. I found that when the temperatures were High enough .. It attempts to engage the compressor. and it seems to make a noticeable differance in the power on a 3.1 litre. I also checked the fuel vs. kilometres and got 14.4 liters to 100 km!!! Very high ... I have since kept it in the off position and use a lighter fan to ventilate the inside and I have managed to average at 12.5 L to 100 km since. But the winter conditions we go through here are going to take a lot out of it this winter unless I can find a diagram to bypass ... So far, I have not found anyone who has it and I have been to throught he avigex files you posted for many things. If you have a serpentine belt diagram for the 3.1 litre it would really help.

Thanks for your time.

Henri

[hforcier]

Just a quick note to say that I managed to find the answer on the Lumina forum and that the changes are already made and working. It occured to me that GM puts the same engine in several vehicles, the answer was availlable with the part numbers and diagrams. Here is the thread:
http://www.automotiveforums.com/vbul....php?p=3458424

Thanks again to all

Henri

[hforcier]

Great News ... The liters per 100 kilometers are consistently at 12.1! This is down from the 14.4 I had originally, a saving of about 16.51 %.
I recommend this modification to anyone who can go without air-conditionning.
The parts cost about 70$ canadian and were self-installed. In the U.S. probably less expensive. With the price of gas here, it pays for itself over time.

Best regards,