Air Conditioner only working on highway
 

My 2010 V70 air conditioner recently stopped cooling the car when parked or in slow traffic. Works fine when driving at highway speed.
Diagnosis is the the pump is pushing down.

Cost to replace the compressor is NZD1,700 (UK850).

Any ideas that could avoid having to buy a new compressor ??

Thanks, Bill

The compressor clutch plate can wear down slightly over time and have an over spec gap between the plate and the main compressor pulley. 0.4mm - 0.6mm is usually the range so 0.6mm is the maximum gap you want to have.
The electromagnet which pulls in the clutch plate weakens with heat which fits with your symptoms of not working at low speed.
Once on the highway, there's enough cooling air movement for the electromagnet to be slightly stronger and overcome the excessive clutch gap.

When a clutch gap is correct, the normal fluctuations in electromagnet strength aren't a problem so basically, measure the clutch gap.

I fixed mine for free https://youtu.be/zOjqjR8Mz64

Alternatively, you may just have low gas which is overcome by the compressor spinning up faster at higher engine speeds.

Measurement or data is the key here.

Does it kick in when stationary in traffic if you rev the engine to say 2,500 rpm?

If you have access to Volvo's VIDA system it would be useful to know if the A/C compressor is commanded or not when in traffic. There are certain conditions (engine temp. etc.) where the A/C is disabled. Do you know if your cooling fans are working okay?

Checking the clutch as described above is your first step still - that and low gas are the route of most A/C problems.

Much appreciated.
Gas is confirmed OK.
I will hold work and get Vida working again. Do the Rev test and check the Clutch Plate.

On my Honda, those same symptoms were because the condenser/radiator was in a bad condition (fins almost all corroded/broken off) and couldn't do it's job unless a huge amount air was being forced through it by forward motion.