maxandtara

Anybody have any experience of using the VOT in general. Like anything that is designed to move, I would think that the failure rate may be higher compared to components that don't move?

see image below from advance auto part # T38904

FOT = Fixed rate orifice tube
VOT = Variable rate orifice tube

When our cars were manufactured the only product available was the FOT. As the name implies it regulates the freon at a fixed rate. orange one below 8E0820177 (0.057" o.d. I think)

Disadvantage of the FOT compared to the VOT is at idle or stop and go traffic.

For the Hot extremely hot summers in the southwest of the USA this will surely help.

They are even selling selling them standard (Ambient temp below 105 F) for extreme heat (Ambient temp above 105 F.)

dvs_dave

Not sure how well it would play with the variable displacement compressors our cars have? Maybe the control sequences already allow for what one of these does? It might also end up confusing the electronics by causing unexpected sensor readings, which results in the system shutting down as a safety measure.

Do you find the AC is not powerful enough for your climate? Have you had it properly regassed lately? Also have you tried turning down the center vent temperature in the MMI? Is your condenser clean?

Having said all that, it could work. Give it a try and let us know how you get on.

maxandtara

Dave,

Thanks for the Reply.

I am double checking my reading. Right now the Low Pressure is above the expected range and the High pressure side is normal.

According to the manuals this is an indication that something preventing the proper circulation of refrigerant or the compressor is starting to die.

Hence, I am contemplating an orifice Tube replacement. From what I have read so far (Variable Orifice Tube), the issue people are encountering is reliability/durability.
But when it works, A/C performance is noticeably improved during stop and go traffic. So, I am really curious if anybody in the group has any experience using the new part.

I have cleaned up the condenser a year ago. I will be putting the cleanup of the evaporator on my list.

Dart

maxandtara

From the most recent information I obtainedb a Variable Orifice tube(VOT) may slightly improve HVAC performance in very hot environments in stop and go traffic.

But similar to the extended life timing belt or the silicone based bushing, though they might be better in terms of performance compared to the OEM parts, the added noise the part brings into the party is not worth the trade of for many A8 owners.

Disadvantages of VOT

• Reliability - its a bi-mental product (technically it has moving parts) more prone to failure.
• Noise - From the posting of the mechanic who installed it in his car. He loves it because of performance. He does not mind the noises it makes when the variable part kicks in when he drives in traffic during those hot Arizona days

Most of the A8 fans out there love the sound insulation properties of the car. So a part creating unnecessary noises, is unacceptable for many.