Orifice tube?

[rtk8892]

Does anyone know how to remove the orifice tube on a b6 s4? Could a dirty one make the ac blow warm?

[924Carrera]

Does anyone know how to remove the orifice tube on a b6 s4? Could a dirty one make the ac blow warm?

In theory it could, but the orifice tube really shouldn't be dirty unless the compressor failed and clogged it with metal shavings. In any case removing it entails discharging your AC. The orifice tube is inside the large coupler connection near your airbox on the AC line. Take that apart with two wrenches, and the orifice tube just sits inside and is held in place by an O-ring that comes with a new one.

In your earlier post you mentioned that the compressor isn't spinning at all. That's not a good sign, as the compressor is direct drive and should be spinning at all times even when the AC is off.

If you do end up having to replace the compressor, a new orifice tube is a highly recommended if not mandatory part.

[rtk8892]

Okay, it would also be in my best interest to replace the dryer too correct? What else should I be replacing to do a new compressor

[924Carrera]

Okay, it would also be in my best interest to replace the dryer too correct? What else should I be replacing to do a new compressor

Yes, anytime you open the AC system for a prolonged time, you'll want to replace the dryer because it will get saturated with water from the air and no longer function. Make sure you get all new O-rings for any connection you plan to take apart. They are cheap, but reusing old ones is a great way to ensure you have a leaky system. Depending on whether or not your compressor driveshaft is seized to the compressor, you may need to remove the water pump as I did, to gain enough clearance to get the compressor out. There are some seals there, so if you're unsure it's probably a good idea to have them on hand just in case. I had to order them during the job and it delayed my progress for a while.

If your compressor truly failed, it is also highly recommended to replace the condensor. Unfortunately these are expensive ($350) and not available aftermarket (there are a few brands that claim to fit, but they are missing the power steering cooler mounting provision...I found this out by buying one). However, if metal shavings from the compressor made their way into the system, modern condensors are very difficult to flush properly because they have such small passages. A flush solution will likely just pass through the unclogged passages, leaving the debris stuck in the others.

You'll also want to flush the AC lines out thoroughly, or debris in the lines could end up in your new compressor and cause a premature failure. You can get some simple flush systems online that basically contain a can of a flush solution. You connect it to an air compressor, then just flush the lines into a waste container. Although such products will usually say to not flush through the evaporator core, removing that core from inside the dash is a massive undertaking and I really don't think it's necessary. Basically just flush in the direction such that any debris collected at the orifice tube flows AWAY from the evaporator rather than into it, where it could get trapped and then resurface when the system is refilled with refrigerant. I actually used a closed-loop flush system when I did mine, but it was a huge pain because the machine was old and didn't have enough pressure. I will be buying one of the simple canister systems to use when I put my B5 back together.

The Nissens compressor comes prefilled with the correct type and quantity of PAG 46 oil. The Denso ones should as well. Some brands may instead have a shipping lubricant in them which has to be drained out and replaced with the correct stuff. Make sure you are certain of this, because inadequate oil in the system will spell a quick death for your compressor.

If you use Bentley or Mitchell (not sure about other guides), do NOT follow the torque spec for the various bolts that hold the AC lines to the receiver/dryer, condensor etc. It has to be a typo, because it's way excessive for a bolt of that size. I attempted to follow this spec without really thinking clearly about the bolt size, and ended up snapping one right off long before reaching that spec. Just tighten them until snug by hand.