1hz Air Cond Upgrade

[GTMAC]

Today I got the cruiser back from an air cond reapir ( compressor and condenser) The guy had a theory as to why the 105's seem to regularly fail at about 130k (I know of 4 vehicles) He suggested that it is becuase the main fan is inadeqaute to cool the condenser leading to the compressor overheating and failing. His solution was to fit two 12inch temp fans to the front of the condenser and wire them to a switch in the cabin or wire it to the power wire on the compressor. Its resonably cheap and easy to do, especially if I do it my self. Any thoughts or experiences with this??

On another note they also mentioned the fan clutch may be on its way out?? It manually spins smooth with light consistent resistance as the manual suggests it should, cooling system works fine. Any other ways to confirm the couplings serviceability??

[HDJ105]

From memory the FJZ105's, possibly only auto ones, did have an additional kit that could be fitted to the a/c that included an electric fan to improve a/c performance. However I don't think many were fitted due to the extra cost.

Some upspec LC's do come with an electric fan, but Toyota use a pressure switch in the a/c to trigger it to come on, so essentially it has to be a hot day and the vehicle at standstill so the system pressure will increase and bring the fan on.

[FourXfouR]

any system can be improved by installing or upgrading a condensor fan. Most factory fans run off the dual function pressure switch ( controls both condensor fan cycling and acts as a high pressure safety cut out as well, this is the best way to do it. However, an easier way is to run it off the factory pressure switch. get a test pencil and check which side of the switch is constantly live and which is switched over. Remember alot of cars use earth switch so if there is no power at the switch, put the test pencil clip onto the positive side of the battery and try again. Once you have found which side is the switching side, tap into this wire and set up a relay so when the switch is activated it will trigger the relay. If you cannot find this wire just tap into the compressor wire and run it to the relay. Doing this will basically cyle the fan on and off with your compressor cycle, not quite as effective as the factory method but it does work pretty well.

If your clutch fan is crook it will have a negative effect on both the a/c and cooling systems

[TonyH]

Refrigeration 101.....

ANy system CAN benefit from additional condensor capacity, but any system CAN also suffer from 'over' condensing.

The best way to add an additional fan to the system is to get an auto lecky to fit a dual pressure switch into the receiver/drier. A 4 wire one with a switch that stops the compressor when excessive or insufficient refrigerant pressure is sensed, and another to 'cycle' the condensor fan. Once your moving at around 20 kph, a fan isn't really gonna help that much, they're more for slow going (say city traffic, or hard low-range work).

If you 'over cool' or 'over condense' the gas at the condensor, it simply looses enough pressure to change state back into a vapour before it hits the TX-Valve (or other RMD). This is exactly what happens when there is insufficient condensor cooling or excessive heat - the gas isn't able to be compressed then cooled enough to turn it into a liquid, so it arrives at the TX'Valve as a gas. The reason this is a problem is that cooling only takes effect when the refrigerant is sprayed through the TX-Valve. The result of the refrigerant changing from a high pressure liquid, being squeezed through a small hole into a low pressure chambers, is that the gas rapidly changes from a liquid into a gas. It takes energy to transform states, and the most readily available energy at this part of the system is heat, so heat is being absorbed.

A fridgy's secret : There is no such thing as cooling, only heat removal!

So it's a delicate system that needs to be understood to make it work better. Throwing a fan on willy nilly will bring the temps down and potentially prolong high temp compressor damage, but it also has the possibility of reduced cooling, and compressor floodback damage if not correctly controlled.

Hope this helps

Cheers

Tony