Is the HVAC part inside the passenger cabin called the evaporator?

What are common evaporator problems?

A good friend had a camry with water(not coolant) on the carpet problem. He said something about "stuck debris". He undid some hose in the engine room, blow compressed air into it. Cured the problem. What was that problem?

Another friend had a volvo with moisture on the windshield problem. He aint no mechanic, so took the car to dealer. Dealer nailed him $1400 for a new evaporator, parts and labor. Could this friend possibly use the other friend's "blow" technique and cure the problem without spending a penny?

 

The evaporator is the unit housed inside the cabin.

This is where high pressure refrigerant from the A/C pump is expanded through an orifice and in so doing absorbs heat. The expansion takes place adjacent to the evaporator which therefore gets cold.

When air is chilled its ability to hold moisture reduces. As a consequence water is deposited on the "fins" of an A/C evaporator during operation. Water drops from the evaporator to the bottom of the A/C unit housing (lowest point) and is piped away underfloor. (hence the puddles left behind by an A/C vehicle).

If the sealing of the A/C unit isineffective or the drain tube leading away from the casing is blocked this can lead to water finding its way onto the footwell carpets or alternatively causes excess misting on the windshield.

Blockage of the drain tube is VERY common since the tube includes a one way valve to prevent air being sucked into the A/C unit via this route (dependent on A/C design). The one way valve is usually a low cost moulded rubber component (like a flattened tube)

The blow process is effective if the valve or tube have become blocked with leaf etc debris allowing a significant amount of water to accumulate and to escape from a hole relatively high in the A/C casing.

Stuart

 

 

Thanks Stew!

Yeah....sleepwalker, u just laughed at poor guy's misfortune. . Why not give some input? I am curious.

 

Sorry I forgot to answer your Common Evaporator problems.

Two main problems with the evaporator. Evaporator Leakage & Faulty Evaporator Valve Operation.

If the evaporator leaks the refigerant is lost from the system and there is (ultimately) no gas left to compress or expand. As refigerant is lost the system become less efficient.

A faulty evaporator valve results in the expansion process being too little or too vigorous. If too little there is insufficient cooling and if too vigorous the system freezes up reducing air flow and possibly spitting water out of the vents etc.

Not quite sure what the optimum temperature is at the evaporator valve (2deg C?) but it is certainly above freezing point and this is the whole purpose of the valve. The valve uses a temperature feedback mechanism to maintain control.

I wish somebody would answer my questions!

Stuart

 

the dealer was right if.... the evaporator is leaking, but no case in volvo like that.

moisture....

the air will first pass the cold evaporator to remove the moisture and drain it out, then the cold moistureless air will pass the heat exchanger giving out warm air.

ever wonder why your compressor still keep on working eventhough you are using the heater?

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Hi Sleepwalker,

The A/C is as good at DEMISTING the vehicle as it is at COOLING it. This is why the DEFAULT setting is ON, UNLESS you turn it OFF manually. Of course turning the A/C OFF = turning EC ON (Economy mode).

I think the latest models have reduced this confusion somewhat by re-labelling EC.

Stuart

 

Uh-oh. He said "orifice."

 

yes. that's right.