[V70, 1999, 2.5 TDI] Air Conditioning - Compressor does not run

[misha]

Hmmm....these cars don't have expansion valve.
They have orifice tube instead.

When compressor seize...orifice tube replacement is a must.

If there is no gas...there shouldn't be that much pressure in the system...in fact...there shouldn't be any readable pressure.

I would go back to ac shop to check the pressure again.

I suspect that there is a blockage in the system...assuming that a gauge you used could be used for ac system pressure testing.

[MichaelPL]

Hmmm....these cars don't have expansion valve.
They have orifice tube instead.

When compressor seize...orifice tube replacement is a must.

If there is no gas...there shouldn't be that much pressure in the system...in fact...there shouldn't be any readable pressure.

I would go back to ac shop to check the pressure again.

I suspect that there is a blockage in the system...assuming that a gauge you used could be used for ac system pressure testing.

I mistranslated the name earlier. We are talking about the same part - I also replaced it (located in the thicker part of the tubing, under the fuel filter).

It seems that I will need to revisit the A/C "machine check."
I will read the fault codes tomorrow after checking the sensor we discussed earlier.

[misha]

It's inside a thinner(high pressure line) not inside a thicker (low pressure line).

Anyway...go back...connect it to ac machine...jump the pressostat near the firewall in order to start a compressor...and gauges will tell you everything.

[aeg]

Evaporator is a weak point on ac system in these cars(p80) because of HVAC system design.

At this age almost all of them already needs to be replaced.

P2 cars don't have this problem.

I replaced mine last year and that was a 3 day job.

What did they change in the P2 cars? Is it possible to retrofit a P2 evaporator into a P80 and solve the problem permanently?

[misha]

It's not about evaporator itself...it's about HVAC system design.

You can slow it down by retrofitting adapter and cabin filter from s,v,c,xc70 series cars...since 850 doesn't have one from the factory.

That...of course... starts counting AFTER evaporator replacement since old evaporator is already degraded and oxidised at some point at this age.

[MichaelPL]

It's inside a thinner(high pressure line) not inside a thicker (low pressure line).

Anyway...go back...connect it to ac machine...jump the pressostat near the firewall in order to start a compressor...and gauges will tell you everything.

Misha, I already "jumped the pressostat" as instructed, and unfortunately, the compressor didn't start. It seems that the issue might lie elsewhere.

I connected the FCR this morning, and it showed new "fault codes": ECC-211, ECC-314, and ECC-312. However, this may be due to the change in the air conditioning panel.

[misha]

Clear the codes and see which one comes back.
Could be that there is too much pressure in the system and high pressure switch closed to protect the system.

You need to take it to ac shop to check the pressure.

At least it's not the evaporator!


When you change damper motor or ac console/module ...re-calibration of damper motors must be performed.
It can be done with diagnostic tool or just drive a car for a few minutes without blower fan on in order to let the system to re-calibrate itself.
After driving...when you turn the engine off...don't turn the key all the way to off.
Let it sit in position I for a few minutes letting the system to store the new values.

It's complicated but it is how it is.

[MichaelPL]

I cleared the codes, and none came back
Fortunately, it's not the evaporator. That's a huge relief

It seems like the pressure might be too high (maybe this 120psi is one of the "hints"), and indeed, the system is preventing the compressor from starting.
It's strange, though, because it worked fine before.

I will go to the a/c workshop as advised

[misha]

Always...when a major overhaul of ac system is performed it is recommended to let the ac work for about half an hour while engine is idling and closely watch ac pressure gauge.

This will allow to spread the new oil evenly in the system.
Here is the spec for ac system cut in & out pressures:

It's for 850....but ac system is the same and compressor type you installed must also be the same like old one.

Even a slightly 10% of overfilling will make problems.

[abscate]

The 1999 model in North America uses different electronics tha the earlier cars.

The low pressure switch controls signals between the ECM and the ECC/ MCC control head

The best way to force compressor operation on a 99 is to jump at relay. 2/22 I the kidney box