Air conditioning service

The Highlander said:
The electric cooling fan motors still run on when A/C off even engine off due engine's radiator. The old school vehicles use clutch fan. No way to tell for me to know. No one teach me how use scantool for HVAC system. Blah. The compressor speed sensor? New to me.

The bad blower motor is easy to check DMM or scope with AMP thru relay or fuse box.
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I've seen the electric fan motor(s) will run continuity until the PCM shut fan relays down after the engine cool down with a key off from ignition switch. Often found in domestic/import vehicles.

With manual HVAC control panel (old school A/C control panel), the electrical circuits are much easier for a novice mechanic. Sometime complicates.
Start with electrical schematic and study it over and over until you get a picture then go to diagnoise the electrical circuit.

I didnt use my scope meter to check amp waveform in a blower motor. I use test light and DMM. Otherwise if the blower fan fuse blown repeats, use amp clamp and DMM (can use scope meter).
 
diehardbiker said:
The electric cooling fan runs entirely separate from the engine. It uses the vehicle electric power to run it. While AC compressor has direct connect with the engine, where it turns the compressor by pulley rather than the vehicle power. The vehicle electric power is not enough to run the compressor.
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For computer controlled vehicles, the PCM use 2 cooling fan relays for single cooling fan or dual (radiator/condenser) cooling fan motors. They are for water temp in engine and high pressure sensor or switch in A/C system. Single cooling fan motor still use with A/C system but this motor have 2 speed... LOW/HIGH.

Newer Toyota hybrid vehicle use electric A/C compressor instead of belt driven, still use electric cooling fans. Even this compressor will run with the engine off or not drive. Fan will run too but not much longer, the computer maybe battery module, will shut the compressor/ fan down to conserve the battery life.
 
Well my Honda has a separate component. One for A/C and one for radiator. They both have fans on it. I'm sure the fan only comes on anytime on the engine radiator, not the A/C part.
 
sequoias said:
Well my Honda has a separate component. One for A/C and one for radiator. They both have fans on it. I'm sure the fan only comes on anytime on the engine radiator, not the A/C part.
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Right, I think I saw a 2005ish Dodge Ram 1500 truck have one similar to your Honda car.
 
deafsmogtech said:
I've seen the electric fan motor(s) will run continuity until the PCM shut fan relays down after the engine cool down with a key off from ignition switch. Often found in domestic/import vehicles.

With manual HVAC control panel (old school A/C control panel), the electrical circuits are much easier for a novice mechanic. Sometime complicates.
Start with electrical schematic and study it over and over until you get a picture then go to diagnoise the electrical circuit.

I didnt use my scope meter to check amp waveform in a blower motor. I use test light and DMM. Otherwise if the blower fan fuse blown repeats, use amp clamp and DMM (can use scope meter).
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The test light? It's will blew up if connection to 24volts from diesel engine. Yeah, I use test light to check but hard to see if it got dim or not like positive should be 12 volts (gasoline and some diesel) sometime it got 6 volts due bad connection or bad ground. So DMM is easy to read than test light. Most of students got cheap test light and it wont dim when it read to 6 volts. Teacher said junk. junk. junk. Mine test light got little dim when read 6 votls which not bad since mine test light can read from 12 volts to 25 volts. (rare to find a test light but it's friendly for gasoline and diesel.) You right, Don't need to use waveform for blower motor, only for fuel system. I try to remember.
 
The Highlander said:
The test light? It's will blew up if connection to 24volts from diesel engine. Yeah, I use test light to check but hard to see if it got dim or not like positive should be 12 volts (gasoline and some diesel) sometime it got 6 volts due bad connection or bad ground. So DMM is easy to read than test light. Most of students got cheap test light and it wont dim when it read to 6 volts. Teacher said junk. junk. junk. Mine test light got little dim when read 6 votls which not bad since mine test light can read from 12 volts to 25 volts. (rare to find a test light but it's friendly for gasoline and diesel.) You right, Don't need to use waveform for blower motor, only for fuel system. I try to remember.
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Diesel engine have 24V circuit? :dunno: If I probe a 12v test light in the 24v power source, fuse in test light will blow, can replace a new fuse.

The reason I use test light is quick check fuses, relays or 12v power source and telltale light. I never probe my test light in the DLC connectors or any 5 volt reference or damage to the computer or module. If the test light shows
dim or slow glow means high resistance or poor ground circuit, what next? Use DMM to measure the volts and voltage drop. My 12v test light will dim when probe 6V circuit of an antique car. You're right. I think the Power Probe have a dual voltage like 12v/24v. I tell you that I never have or own a Power Probe that every electrical techs have them. I own a cheap test light and homemade jump wires. Cost me 2 cent.
 
deafsmogtech said:
Diesel engine have 24V circuit? :dunno: If I probe a 12v test light in the 24v power source, fuse in test light will blow, can replace a new fuse.

The reason I use test light is quick check fuses, relays or 12v power source and telltale light. I never probe my test light in the DLC connectors or any 5 volt reference or damage to the computer or module. If the test light shows
dim or slow glow means high resistance or poor ground circuit, what next? Use DMM to measure the volts and voltage drop. My 12v test light will dim when probe 6V circuit of an antique car. You're right. I think the Power Probe have a dual voltage like 12v/24v. I tell you that I never have or own a Power Probe that every electrical techs have them. I own a cheap test light and homemade jump wires. Cost me 2 cent.
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Yep, not all diesel engine are 24 volts, some of them. Fuse? Lucky, mine test light dont have fuse at all. I heard of Power Probe and I don't want to spend $$ on it. What's if i lost it at customer's car and drive away and I lost $$. No thanks. I am fine with a cheap $15 test light for 12-24volts. Homemade jump wires. Smart. My father did same thing from radio shack. Nothing to wrong with it and easy to repair.
 
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The Highlander said:
Yep, not all diesel engine are volts, some of them. Fuse? Lucky, mine test light dont have fuse at all. I heard of Power Probe and I don't want to spend $$ on it. What's if i lost it at customer's car and drive away and I lost $$. No thanks. I am fine with a cheap $15 test light for 12-24volts. Homemade jump wires. Smart. My father did same thing from radio shack. Nothing to wrong with it and easy to repair.
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:lol: I dont think you lost Power Probe. You can spot the long cable then you know where PP is. One negative on Power Probe is I can't hear beep beep from PP while probe the voltage present (I dont know exact) and 15 or 20 feet long cable that allow you connect the battery in the front and take PP with you , walk toward the rear of the vehicle to check the electrical circuits or active fuel pump. One trouble with cable is Trip over the cable, no comfy with long cable, Finish the electrical test, you have to rolling up the cable and put PP back in a box. That is why I resist to buy a PP
 
24 volt system, very high chances are they are designed for military uses, it does not necessarily limited to Diesel, there are 6, and 24 volts exists on gasoline engine. I highly doubt 6 volts exists on Diesel because in order to start Diesel engine need heater coil and I doubt 6 volts is sufficient.
 
diehardbiker said:
24 volt system, very high chances are they are designed for military uses, it does not necessarily limited to Diesel, there are 6, and 24 volts exists on gasoline engine. I highly doubt 6 volts exists on Diesel because in order to start Diesel engine need heater coil and I doubt 6 volts is sufficient.
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You missed the point about 6 volts, If there is 6 volts (should be 12volts for that system) then some test light will dim that's mean it got high resistance or poor ground that we talked about.

Which 6 and 24 volts exists on gasoline system you said?

Not just for military only, there is semi-truck which I worked on it for fuel system and rebuilt diesel engine a lot. There is diesel fuel shutoff valve, starter, alternator and other are 24 volts for most BIG diesel engine like around engine 12L or up.
 
deafsmogtech said:
:lol: I dont think you lost Power Probe. You can spot the long cable then you know where PP is. One negative on Power Probe is I can't hear beep beep from PP while probe the voltage present (I dont know exact) and 15 or 20 feet long cable that allow you connect the battery in the front and take PP with you , walk toward the rear of the vehicle to check the electrical circuits or active fuel pump. One trouble with cable is Trip over the cable, no comfy with long cable, Finish the electrical test, you have to rolling up the cable and put PP back in a box. That is why I resist to buy a PP
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The PP's cable is long enough for semi-truck and trailer? :giggle:
 
I never said just for military only. I just happen know that Military is one of few that uses 24VDC

On older european cars uses 6 volt, same with motorcycles.

They aren't as common as 12v

cool :)

The Highlander said:
You missed the point about 6 volts, If there is 6 volts (should be 12volts for that system) then some test light will dim that's mean it got high resistance or poor ground that we talked about.

Which 6 and 24 volts exists on gasoline system you said?

Not just for military only, there is semi-truck which I worked on it for fuel system and rebuilt diesel engine a lot. There is diesel fuel shutoff valve, starter, alternator and other are 24 volts for most BIG diesel engine like around engine 12L or up.
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diehardbiker said:
I never said just for military only. I just happen know that Military is one of few that uses 24VDC

On older european cars uses 6 volt, same with motorcycles.

They aren't as common as 12v

cool :)
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Ah older european cars. No wonder I don't see 6volts anywhere.
 
The Highlander said:
Yep, not all diesel engine are 24 volts, some of them. Fuse? Lucky, mine test light dont have fuse at all. I heard of Power Probe and I don't want to spend $$ on it. What's if i lost it at customer's car and drive away and I lost $$. No thanks. I am fine with a cheap $15 test light for 12-24volts. Homemade jump wires. Smart. My father did same thing from radio shack. Nothing to wrong with it and easy to repair.
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I've see some old test lights that came with bulbs and special fuses (clear glass fuse type). Mine is SnapOn test light have special fuse (thin filament inside fuse), spare extra fuse in handy.
 
diehardbiker said:
24 volt system, very high chances are they are designed for military uses, it does not necessarily limited to Diesel, there are 6, and 24 volts exists on gasoline engine. I highly doubt 6 volts exists on Diesel because in order to start Diesel engine need heater coil and I doubt 6 volts is sufficient.
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Sounds right me. Heater coil? Yes, you forget to add one thing.... glow plugs. Today's diesel powered trucks have 12v batteries like 2 or more batteries in the side box.
 
The Highlander said:
The PP's cable is long enough for semi-truck and trailer? :giggle:
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yup, perfect for semi-truck. My deaf mechanic from another station, told me that he bought a new PP even he is not electrical expert cuz he want to challenge with me like he show me his things. He told me that he probe his PP into the female terminal in the fuse/relaybox, he activate a live power into the ground side by mistake. He realized the PP have voltage protector, didnt blow fuses in his PP. PP have super smart computer that can sense the voltage or ground or short circuits that PP can prevent the dumb mechanic to damage the electrical circuit/components. Sounds cool?
 
The Highlander said:
Ah older european cars. No wonder I don't see 6volts anywhere.
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Yes old Euro cars still have 6 volts. My ex-65 VW bus with a 6-volts system that I converted to 12v starter and generator and no all bulbs change, just leave. The headlights were very brightly, none of other bulbs burnt out.
 
Hey, some of you guys thought that I was exaggerated about truck that has ability to pull 23 tons. Here is link that proves that I was wrong because I underestimated its power.
Ford Powerstroke pulls 280,000 lb train... - YouTube
BTW, I can see why you think impossible. Even though it is possible but it would seriously compromise the safety and structure integrity.
Sheesh 280,000 lbs pulled.
 
diehardbiker said:
Hey, some of you guys thought that I was exaggerated about truck that has ability to pull 23 tons. Here is link that proves that I was wrong because I underestimated its power.
Ford Powerstroke pulls 280,000 lb train... - YouTube
BTW, I can see why you think impossible. Even though it is possible but it would seriously compromise the safety and structure integrity.
Sheesh 280,000 lbs pulled.
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Oh, wrong place in A/C forum.
 
I have client guard because something issues kind of on reason point, they depend on the A/C expensive!
 
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