AC overhaul - Compressor upgrade? Condensor?

BowhunterBrown said:

But isn't 15 amp undersized?

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PlayingWithTBI said:

That's why I'm running the A/C Clutch straight off the battery getting 14+ Volts instead of 11.4 measured at the clutch.

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Adding this - the higher the Voltage, the lower the Amperage. Plus, less wear and tear on components.

PlayingWithTBI said:

Adding this - the higher the Voltage, the lower the Amperage.

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^^^???

I have been testing with higher capacity compressor and it did show an improvement. Going from large serpentine condenser to the smaller (only one I could locate after multiple returns) parallel flow was almost of no difference. I also have issue with underhood heat and at speed get hot air pushed from engine that raises vent temp about 3* C. 1.5k to 2k rpm city driving around 35 -45 mph currently best vent temp, while at highway speed in same rpm range vent temps go up and have direct corelation with engine temperature.

1998_K1500_Sub said:

^^^???

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Ohm's Law. If I can feed 14 Volts to the clutch, it'll draw less amperage to do its job. Thus allowing for a smaller fuse and wire size. Think about the 20,000+ Volt overhead wires on the electrical grid and the size of the wire supplying service to LA from PHX as an example. Just about all of the energy produced at our Palo Verde Nuclear Power Plant is sent to LA, CA

I'll shut up, you know what I mean

PlayingWithTBI said:

Ohm's Law. If I can feed 14 Volts to the clutch, it'll draw less amperage to do its job. Thus allowing for a smaller fuse and wire size. Think about the 20,000+ Volt overhead wires on the electrical grid and the size of the wire supplying service to LA from PHX as an example. Just about all of the energy produced at our Palo Verde Nuclear Power Plant is sent to LA, CA

I'll shut up, you know what I mean

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A clutch is a resistive load.

Ohm’s law says if one increases the voltage across the resistor, there is proportionally more current

Since power is the product of current times voltage, it’ll also consume more power

I know what you’re thinking, but that doesn’t apply here

1998_K1500_Sub said:

A clutch is a resistive load.

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I think it is up to the point it's completely engaged, then the load is only holding it in place.

As an example on a transformer. let's say 480/240 3PH (that's a resistive load too). If you're not drawing any loads on the 240V side, the 480 side doesn't draw hardly anything.

1998_K1500_Sub said:

A clutch is a resistive load.

Ohm’s law says if one increases the voltage across the resistor, there is proportionally more current

Since power is the product of current times voltage, it’ll also consume more power

I know what you’re thinking, but that doesn’t apply here

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I agree with you. A field coil like an ac clutch or ignition will draw more power with higher voltage, but an electric motor like a fuel pump or blower motor will draw less.

Also since a few on another site were claiming my vent temps are not even close to possible. Once again compared two measurement devices. The air is also extremely cold holding my hand in front of the vents. I also put the thermometer in a cup of ice water and also shot the ice water with the IR. Both read around 32F in ice water that had been sitting for 10 minutes.

PlayingWithTBI said:

I think it is up to the point it's completely engaged, then the load is only holding it in place.

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It's resistive in the steady state, that's the nature of a DC electromagnet, so we're fully in the "E=IR" realm.

It certainly is inductive, but the effect of the inductance is a very short-lived turn-on / turn-off transient event, not a steady-state concern. The inductance is what warrants the use a flyback diode.

PlayingWithTBI said:

As an example on a transformer. let's say 480/240 3PH (that's a resistive load too). If you're not drawing any loads on the 240V side, the 480 side doesn't draw hardly anything.

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Yeah, we're getting away from DC circuits, let's save this AC analysis for another forum where they talk about kVA, VAR /power factor / reactive loads / real and imaginary power, open deltas, wild legs and such

L31MaxExpress said:

an electric motor like a fuel pump or blower motor will draw less.

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This isn't true in general for electric motors.

In our vehicles (GMT400s) they use permanent magnet DC motors, so that's the context.

A motor, say in an electric seat, will draw increasing current with increasing applied voltage.

A motor would draw less current at higher applied voltage if the torque required by the load (pump or squirrel cage fan) actually decreases with increasing speed. I suspect you've witnessed this.

A pump or squirrel cage fan may well have non-linear behavior, where the torque required vs. speed increases at first and then knees-over at some critical speed and thus unloads the electric motor.

Centrifugal superchargers have a behavior of this sort, do they not? They unload under certain conditions, IIRC.

I'm not an ME so fans / pumps and their behavior in liquids / gasses isn't in my wheelhouse.