Scenic 04 A/C repair

Post your Cit/Peu/Ren air conditioning queries or advice.

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steelcityuk
Posts: 1053
Joined: 03 Jul 2006, 21:51
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Scenic 04 A/C repair

Post by steelcityuk » 08 May 2013, 12:05

Hi Folks,

After a number of other jobs on the Scenic it was time to tackle the A/C system. Out came the Ariazone a few weekends ago to check for any system pressure, the A/C had never worked since buying the car so I was expecting the worst, busted condenser or cracked joint.

Drawing a deep vacuum on the A/C system showed no sign of leaks even after several days. I bought a bottle of EZ Chill to refill the system - £24.99 + £10 bottle deposit. Despite the system seeming intact there was a problem with it. After filling with just a small amount of refrigerant the compressor cut in (and out) but there was no cooling effect from the vents, this didn't surprise me because there wasn't enough refrigerant for the system to operate correctly. I decided that the system must have a blockage that was allowing a small amount of charge to build up enough pressure to trigger the pressure switch. My suspicions fell on a blocked Orifice tube.
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The High/Low pressure pipe containing the Orifice tube was cut open using a mini pipe cutter. The Orifice tube didn't look that dirty. So the decision was made to remove the compressor, clean it up, drain the oil and refill it with 150ml Polyol Ester oil with UV dye. The accumulator was drained and the rest of the system flushed.
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Here's the repair piece I bought from the US, it cost just £15 inc delivery. Renaults' solution is to buy a complete pipe. No doubt this would be expensive because the pipe is several feet long and goes from metal to rubber to metal again. Also fitting it requires the removal or bending of the heat shields in the engine bay.
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After deep vacuuming the system for an hour and checking for leaks, the system was charged with the correct amount of refrigerant with the engine running. The cut in and cut of the compressor varied the pressure on the low side of the system from 27 to 43 psi, there's no high pressure service port on the Scenic. An infrared thermometer showed a post condenser/ pre Orifice tube reading of 39C with an ambient air temperature of 12C.
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So here's the reading post Orifice tube. The temperature difference is 35C. Frost is beginning to form on the pipe work and accumulator. The compressor cycles on and off OK.
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Before tuning on the A/C the reading was 34C, in a closed car on a hot sunny day. After 5 minutes it's reading 3C. So even though it's a uncalibrated device that's still an impressive difference, needless to say the air feels very cold.
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steelcityuk
Posts: 1053
Joined: 03 Jul 2006, 21:51
x 1

Re: Scenic 04 A/C repair

Post by steelcityuk » 22 Jun 2013, 21:56

When the air conditioning failed just a couple of weeks after vacuum testing the system, flushing it and replacing the orifice tube I thought it had sprung a leak, connecting up a manifold gauge proved this idea to be wrong. So I connected up the Clip which indicated that there was no pressure in the system, my thoughts turned to a bad connection, faulty switch or another blockage. Despite waggling the connector, cleaning up the contacts, spraying with switch cleaner, Clip couldn't get a reading so I thought it must be the pressure switch. It wasn't and testing with a DMM between the pressure switch connector and the injection ECU connector showed the pressure switch connector was faulty. I got hold of another connector from a newer Scenic and soldered this onto the loom. Apparently this is a common fault know to Renault under a technical bulletin - OTS 0b07 or 0b08?

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Searching the web brought up some interesting information. On some Renaults a drop in refrigerant pressure or faulty compressor connection can trigger a fault code (DF1070?) that will stop the air con working by blocking engagement of the compressor until the faults are cleared, so if you use an independent for air con service be aware they may not be able to get it working even if the system is gas tight and charged. Renault do have a fix for this which done under OTS 0b07, 0b08 and 0b17, these fixes include loom repairs, new software and a replacement compressor.

Steve.