Thread: TD5 Airconditioner efficiency.

Originally Posted by TonyC

Others on here understand AC better than me, but.

Is it gassed properly? Given it had a new compressor in May I assume so.

Is the compressor running all the time or cycling, if cycling is it the thermostat in the evaporator, or the pressure switch in the dryer, that's switching off the compressor?

Tony

I assumed it was running full time (because the temp was fairly stable) but I will check that on the weekend.

So update. Went for a drive yesterday (not a common occurrence for me). It was much much cooler outside. Mid-high twenties. Vent temps were typically 6-8 which works. Maybe that isn't so helpful.. if the weather is cool my ac works fine.

So while on the trip we were driving back from the desert. I was seeing coolant temps in the mid 100 range, which is higher than I've seen before. It was hot (39 ambient) but still that's pretty hot. I'm thinking first port of call might be to replace the clutch fan. Even if it doesn't help the AC I think that might help engine temps. I spun the fan just then, and when cool there is a lot of resistance. Feels the same hot or cold.

The other thing that might be next on the list. The condenser is showing signs of sitting on the front of a car for 20 years. Corrosion and general deterioration.

Thanks to chat GPT I found this mob which do a parallel flow drop in replacement.

LR025985 - High Performance Air Con Condenser for Land Rover Defender TD5 and Puma 2.4 and 2.2 Vehicles - Air Conditioning Condenser and Fan - by Coolair Logan

Originally Posted by Captain_Rightfoot

So update. Went for a drive yesterday (not a common occurrence for me). It was much much cooler outside. Mid-high twenties. Vent temps were typically 6-8 which works. Maybe that isn't so helpful.. if the weather is cool my ac works fine.

So while on the trip we were driving back from the desert. I was seeing coolant temps in the mid 100 range, which is higher than I've seen before. It was hot (39 ambient) but still that's pretty hot. I'm thinking first port of call might be to replace the clutch fan. Even if it doesn't help the AC I think that might help engine temps. I spun the fan just then, and when cool there is a lot of resistance. Feels the same hot or cold.

The other thing that might be next on the list. The condenser is showing signs of sitting on the front of a car for 20 years. Corrosion and general deterioration.

Thanks to chat GPT I found this mob which do a parallel flow drop in replacement.

LR025985 - High Performance Air Con Condenser for Land Rover Defender TD5 and Puma 2.4 and 2.2 Vehicles - Air Conditioning Condenser and Fan - by Coolair Logan

By mid 100s I assume you mean 105, not 150.
From what I've read on here, the TD5 AC is controlled by the ECU, but I may be confusing it with a Disco TD5, so if your coolant temps are up, the car maybe switching the AC off.
Shack would know

Do you have a Nanocom? Can it tell you if the AC compressor is on or off?
If it's running all the time I'd be suspecting it's under gassed.

I'm no AC expert so If anyone thinks I'm off track please chime in.

Tony

Originally Posted by TonyC

From what I've read on here, the TD5 AC is controlled by the ECU, but I may be confusing it with a Disco TD5, so if your coolant temps are up, the car maybe switching the AC off.
Shack would know


Tony

The engine ECU on both the D2 and Defender will both turn off the A/C when the engine temp reaches 116° with only 1° hysteresis to cycle back on.

On the D2 the ATC controls A/C functions, but requests get passed to the engine ECU which then relays the final requests to the individual components.

On the Defender, operation is very similar only the ATC is missing and a small "unit- Air conditioning" is used instead.

Let's do some mental diag...

The compressor on the Defender will cycle for 3 reasons.

1. requested evaporator temperature has been reached (included in this is if the evaporator is in danger of freezing).

2. system pressure has risen too far.

3. Engine temperature is too high.

If system pressure is getting too high the condenser fan will switch on before the compressor will be disabled.

If the compressor is turning off BEFORE the condenser fan turns on, then it is being cycled by the thermistor and A/C unit, due to the evaporator temp having been reached.

If the compressor is cycling without the condenser fan running before the air from the vents gets very cold

( and I'm sorry here as there is no definitive temperatures given in any official document that I've found, and I haven't been able to test a good one....)

then it's LIKELY that either the thermistor or A/C unit has failed.

It's unlikely that the A/C will cycle off due to low pressure once it has started.

This only applies to the TD5 Defender.

Hope that helps!

Originally Posted by shack

The engine ECU on both the D2 and Defender will both turn off the A/C when the engine temp reaches 116° with only 1° hysteresis to cycle back on.

On the D2 the ATC controls A/C functions, but requests get passed to the engine ECU which then relays the final requests to the individual components.

On the Defender, operation is very similar only the ATC is missing and a small "unit- Air conditioning" is used instead.

Let's do some mental diag...

The compressor on the Defender will cycle for 3 reasons.

1. requested evaporator temperature has been reached (included in this is if the evaporator is in danger of freezing).

2. system pressure has risen too far.

3. Engine temperature is too high.

If system pressure is getting too high the condenser fan will switch on before the compressor will be disabled.

If the compressor is turning off BEFORE the condenser fan turns on, then it is being cycled by the thermistor and A/C unit, due to the evaporator temp having been reached.

If the compressor is cycling without the condenser fan running before the air from the vents gets very cold

( and I'm sorry here as there is no definitive temperatures given in any official document that I've found, and I haven't been able to test a good one....)

then it's LIKELY that either the thermistor or A/C unit has failed.

It's unlikely that the A/C will cycle off due to low pressure once it has started.

This only applies to the TD5 Defender.

Hope that helps!

What makes the system pressure to go high? That the condenser can't shed enough heat?

If the system is not cycling but not getting really cold, is low gas the likely culprit?

Tony

If the condenser fan isn't running, then possibly yes.

I can't remember what bits you have replaced, but a faulty TX valve or compressor can also be the issue.

I should point out that the temps I quoted are when driving at 70+kmh and I have over ridden the thermistor but not the pressure switch. I have a faulty thermostat or A/C unit.

Ok so update from testing.

The TD5SPY doesn't have the functionality to report if the compressor is on. However it does have a test button where you can test various systems while the car is off. The test button for the fan worked, and for the compressor also worked. Clearly the ECU is actively controlling these.

So I went for a drive around town .. not long but it's hotter today. 30 ish. The engine temp didn't get above 89. Vent temps on the ac were 6-8 when I left home and the car was cool. After parking in the sun for a bit they were around 10-11.

So I sat the car in the driveway and left it idling to try and get the temp up. It didn't really get above about 89. The compressor was running the whole time AND the condenser fan. Vent temps were 14!!!

I shut the engine off and ran around and tried to spin the clutch fan. It was spinning very freely. Even more freely than when cold. Like a turn or maybe more.

Work completed so far. new compressor, new TX valve, obviously a full regas. Evaporator cleaned. Condenser is as clean as a 20 year old condenser gets.

PS I don't know what's wrong with this thing - but it feels as though it needs significantly more capacity for when it's hot.

Originally Posted by Captain_Rightfoot

So I sat the car in the driveway and left it idling to try and get the temp up. It didn't really get above about 89. The compressor was running the whole time AND the condenser fan. Vent temps were 14!!!

Get it like that again, then give the condenser a squirt with the hose and see what happens.

Idling is not a good test. The compressor isn't moving much gas and the fan isn't pulling a lot of air through the condenser. You really need to be sitting around 1200-1500 rpm for a representative test. Lots of systems suck at idle and not moving.